I've been to Trexler a few times this year now and I've seen it mentioned in a few threads but didn't see a specific thread for it. So here's a little info for those who may want to check it out.
First, one thing I've heard a bunch of times is that Trexler is fun but short. I get why people say that, but the truth is it's actually bigger (and more challenging) than a lot of people realize. If you're absolutely opposed to repeating any section of the trail, then it's necessarily short. But if you're willing to do a mile or so of repeated trail, you can easily get 20 miles. The trick is to hit the whole boundary trail, and then loop back to hit the pump track sections and the awesome flow trail descent (one of the most fun trails I know in the entire region.) The section a lot of people miss is circled below.
View attachment 135391
Also, the ride shown here starts from then Orchard Rd. Parking area. There is a parking area that starts within the park closer to the pump track, but the Orchard Rd. lot puts you right on the boundary trail that allows you to choose how long (and hard!) your ride is.
Second, there is a TON of climbing if you do the boundary trail. If you stay just in the middle of the park where the pumptrack is, there isn't too much - you just have to go from the bottom of the pump track to the top to redo it. But the boundary trail has something like 200-250 feet of elevation gain per mile. There's plenty of descending as well, but the climbs are tough. In fact, if you go clockwise on the boundary trail, there is a climb near where it links up to the center of the park that's almost impossible to clean - super loose and steep at the bottom and then steady and long for another quarter mile or so past that. And it's all exposed, so it can cook you in the summer.
Finally, the Valley MTBers put a lot of work into these trails - in fact, every time I've been there other than on New Year's Day, they been out working on something. So the trails feel very flowy in the sections they work on. They're not allowed to change the boundary trails as I understand it (which is a shame because that one brutal climb could really benefit from some contouring.) Between the flowy stuff they work on and the boundary trail, the whole place has a nice mix of chunky and flowy - again, with a shit ton of climbing thrown in.
I'm attaching the GPX file from the ride pictured above. There is some repeating of sections here, but it's worth it to justify the drive out and get a chance to see everything the park has to offer.