Well I registered for our local Margarita Ride. It's on September 10. Here are the options:

15-mile route to the lookout point across the bridge over the Missouri River (a majority of which is flat)
35-mile loop through Meckling and around the bluff (relatively flat route)
45-mile loop through Meckling and climbing out of the bluff bottom (a few hills)

Now, my ride is a Trek 7200 hybrid with a big cushy seat, that I'm not certain I care for. I tend to scoot toward the back of the seat.

I tend to ride 10-15 miles a couple days during the week with a 20 mile ride on the weekend. Yesterday I did 25. I started getting tired toward the end, so I'm not sure about the 35 mile option. But, I'd like to try it since there will be other people around and it won't really just be me. Yesterday I wore a pair of jogging shorts with the liner sewn in... that pair works up to 15 miles or so, but otherwise the shorts ride and dig in a bit and are all around uncomfortable. I should've worn my bicycle shorts, though they're unpadded.

I did have a soy protein drink before my ride and a granola bar, that was my breakfast. I was starting to get a little hungry, perhaps I should've had something along to snack on. I had 2 water bottles along, which was fine for 25 miles, but probably wouldn't be for 35. I rode 10 miles in 45 minutes, 15 in 1:06, 20 in 1:28 and 25 in 1:45-1:50 ish. I slacked off the last few miles.

I guess that I should find out if they'll have a water stop. I don't have the cash to buy a hydration pack.

Any advice? I'm feeling encouraged by your words of wisdom in this thread.