It sounds like you're feeling the same way I was after I finished my first sprint orienteering tournament, the first Sprint the Golden Gate
I made the SART bracket literally the next week. In 2009. CascadeOC didn't have any sprint maps then, and I was still five years away from making my first map.
Anyway, so I get the feeling of "OMG, sprint tournaments are amaaaaaazing!"
You asked for some thoughts, so here are some.
Bracket Size & Format
There's more than one way to skin a cat here, so before you mirror the SART format exactly, think about how many people you think you'll get and how many maps you have (or want to make). The San Francisco tournaments that I went to (2009, 2011, 2013) all had attendances in the 30's, so the brackets were a lot smaller. The 2013 tournament was just 3 rounds all in one day.
In 2009 and 2013, there was an interval-start "prologue" on Friday afternoon. It was not mini sprint, and not everyone attended, so the tournament seeding was basically the event director subjectively ranking everyone based on prologue results and what he knew about non-prologue runners. One time, there was a vacationing Finn who registered but didn't run the prologue. He was given a really really good seed, and turns out, he was basically like me: a sort-of fit, but not super-fit, serious-but-still-recreational orienteer.
When I built my tournament, I wanted to take all subjectivity out of it, which is why we have a Saturday morning mini-sprint to rank everyone. It's not perfect (eg: Eric Bone skipping it, getting a low seed, and basically screwing Tori Borish out of winning the women's competition). But, tournaments aren't perfect. A lot of crazy stuff happens in the NCAA basketball tournament.
Conclusion: you can have a time trial included, or an optional prologue, or nothing and rank 'em how you want to rank 'em.
For weekend scheduling, I kinda followed Vancouver's Sprint Camp scheduling: the most people are there all day Saturday and morning Sunday. They have other events on Friday afternoon and Sunday afternoon, but attendances aren't as high. For a tournament, you want just about everyone, so that's why there's nothing on Friday and we're doing awards mid-day Sunday.
Based on scheduling, I figured that we could do 3 tournament rounds on Saturday and 2 on Sunday, and this fit in well with ideal heat sizes (4-6) and how many people I thought we could get to a Seattle event. Vancouver gets 100+ for Sprint Camp; for a first year event in Seattle with zero sprint track record, I didn't think that we'd get 96 (16 heats of 6), but I thought that we'd get well over 64 (16 heats of 4), so we met in the middle with 80, and that's been just right so far. It's easier to add more if it's popular than to take away if it's not.
If you don't think you can get 80 (or even 64) to Okanogan, or if you don't have enough maps, or if the distances between venues aren't convenient, you could do one round less than SART. 4 rounds instead of 5 would mean 8 heats instead of 16. 8 heats of 6 is 48 runners. This is all assuming that each round halves the field, and you don't have to do that, either. In the 2013 Golden Gate event, it was 6 heats of 6 runners with 3 tournament rounds. The first round results split runners into three groups of 12 (top, middle, bottom). The second round split those 12's in half into 6's, and then the final round finished it.
One other difference between Golden Gate and SART was that Golden Gate allowed for spot-stealing, starting with the 2nd round. So, if you were in the bottom half of the bracket and had the fastest time, and it was faster than the slowest time from the top half of the bracket, then you'd swap places. This was a clever bit, theoretically, but in reality, it was confusing to re-work the bracket in real-time. This may have been mostly in part to the tournaments not being very well organized, to be honest. I was just a participant, but I was also the biggest bracket enthusiast, so I was tasked at all three tournaments I attended to figure out the brackets based on the results print-outs the event director gave me. The bracket rules were a lot more confusing than SART, so I'd be sequestered away from the other participants (who I wanted to hang out with) trying to figure out where everyone was supposed to go next. I didn't like it. Which is why SART is actually pretty simple (despite the bracket looking complicated).
Logistics matter. From a competitor standpoint, you want the best courses on the best maps. From an organizer standpoint, you want things to run smoothly. Compromises need to happen. SART Saturday in 2016 had 4 daylight races at 4 different venues, so that meant setting up and taking down 4 times in one day (and a shorter day than this year because there wasn't a night-o). It was pretty stressful, especially because we have a small crew. I'll be the first one to admit that Round 4 this year at SSC wasn't great from a competitor's perspective, but it was nice to have just one place to hang out all day (CascadeOC tacked on a local score-o in the afternoon, too). In 2015, we had Rounds 2 and 3 at NSC and the compromise there was that re-used the same terrain. That said, some venues don't need compromises! Rounds 4 and 5 in 2015 and 2016 were on maps that could have two independently great courses. But neither of those venues were brand new, so that's a consideration, too.
Conclusion: think about how large your attendance will be, and the logistics, quantity, and quality of venues before deciding on how you'll set up the bracket.
"In Seattle, they sold out with 80 people, but only needed less than 10 volunteers (a number of whom could compete in the events) to run the entire event."
Each year, we've had a volunteer staff of 8, none of whom competed in the events, and only one who realistically could have (the one who brought all of the food). 6 of the 8 are basically just day-of-event volunteers.
Start Chief: We give her the start lists, and she makes sure that everyone clears, checks, and starts on time with the correct maps.
Finish Chief: She preps all of the race timing files and writes the code to ensure that we get the bracket assignments correct. This role is actually more complicated than just one sentence.
Food Chief: She brings all of the food and sets it up.
Course Setting Team: I have a team of four that does all of the setting, vetting, and take down. (And we only had three on Sunday because one overslept). They seem like magic to me because we meet on Saturday morning, I give them all of the stands, cones, flags, SI boxes, and course-setting maps, and then everything. just. gets. done. Having four was essential in for Saturday in 2016 with four venues; we had two teams of two. One team set, vetted, and took down the Time Trial, and then leapfrogged the event and went straight to Round 2 and repeated. The other team did Rounds 1 and 3.
Event Director & Course Designer: And then I do all of the rest. This role is actually more complicated than just one sentence.