My wife and kid are driving down to Del Rio tomorrow (actually to Ciudad Acuna) to visit their mother / grandmother. I am quite familiar with Del Rio and go there often.
If you go across to Mexico, there are lots of places you can get some good authentic Mexican food. Don't drive across, there are good places to park on this side that have security (vigilancia) and have taxi service too and you can take a taxi across pretty cheaply. Don't accept the first price you get on the taxi ride by the way, make an offer of about 60% of the original price offered (usually about $20USD for 2 people) and work up from there. After you get a price set, the driver is usually quite friendly and most of them speak fairly good (albeit broken) english. Ask your taxi driver to drop you off at a good place to eat (try Lando's or La Macarena, they are very accomodating to people from north of the border) and then go for a walking tour downtown at some of the shops for souveniers. P.S., it would be somewhat of an insult to try to bargain on the price of the meal, that's the one thing that's off-limits when it somes to trying to get a lower price, but fortunately it's usually worth every penny of it! Bargain the price down on everything else, though- it's expected! Nightlife in Acuna is one of the most attractive things about the town, and if you decide to spend the night there, stay in the Best Western Villa Real. It's close to downtown and it one of the safer places to stay in Acuna. Pass up any offers to be taken to "Boy's Town". While that's where you can get some real "action", you can also get some stuff that soap won't wash off!
Rodeos take place many weekends in Acuna, ask you taxi driver about it and he might be able to assist you in finding one. Beware though, the rodeos end up being bullfights with Matadors sometimes!
In and around Del Rio, you can go take a swim in the little river draining from San Felipe springs at a park on the east end of town on Hwy 90. Laughlin Air Force Base is about a 15 minute drive out the same highway and they fly T-6 Texan II
's, T-1 Jayhawks and T-38's. You can park along the highway or close to the entrance and get some good pictures.
Lake Amistad (friendship) is a few miles north of town and offers some good bass fishing. The lake level is coming back down a little from the recent peak about a year ago and that makes for some good fishing conditions. About 40 miles west of Del Rio on Hwy 90, you'll drive over the tallest bridge in Texas, where the Pecos river meets the Rio Grande and it's quite scenic out in that area.
If you have any specific questions, feel free to ask me and I'll try to help!
"A fear of weapons is a sign of retarded sexual and emotional maturity" -Sigmund Freud