Nichol's Landing Paddling Trail
As my first time on whitewater, this was a perfect place to start. Rapids were nice and mild this time of year but still enough drops and chutes to flip the boat if you weren't on your game. Water is very nice and varies from narrow, rocky fast and shallow to wide, slow and deep. Cypress line the shore the whole way (providing shelter to lots of creatures friendly and not.)
During this time of year, tubes always pack the river but quickly seem to disappear. This is also dependent on what part of day as they don't show up until after lunch and disappeared before 5.
Water levels can be fairly low at times so you may find a few rocks, especially in the faster parts. Most beginners wouldn't find anything to fear as all the rapids had an easy portage or an alternative route (I took 3 poorly-skilled first timers who safely went through everything I went through.)
All in all, great 4 or 5 hour trip and with lots of local outfitters, easy and fun access for both beginners and the seasoned pro.
Bigfoot Canoes and Guadalupe Canoe Livery seem to be the heavy hitters out here.
$5 charge to park at Nichols Landing park but there was no attendant collecting or honor box when I was there.
From San Antonio:
1604 to 281 N. Left on Spring Branch Rd, follow signs to Nichols Landing.
290 W to 281 S, Right on Spring Branch Rd, follow signs to Nichols Landing.