Here are some suggestions of places in the Dallas area (taken from The Texas Dog Lover's Companion by Larry D. Hodge)

Cedar Hill State Park (3.5 paws rating)
http://www.tpwd.state.tx.us/park/cedarhil/
- dog accessible beaches (shores slope gently to the water and the beaches are generally free of rocks and grass in the sand)
- hiking trails
- scenic views
- dogs must be on leash
- the park has the Penn Farm Agricultural History Center in it which sounds very interesting
- located 15 miles south of Dallas on FM 1382
- entrance fee: $5 per person

Dallas Nature Center (3 paws rating)
http://dir.gardenweb.com/directory/dnc
pictures: http://www.walktx.org/DNatureCtr.html
- $3 per car donation to enter
- 9 trails with biological diversity
- located 2 miles south of Interstate 20 at 7171 Mountain Creek Parkway

There are some others listed in the book, but they have lower ratings. I can read more about them and post more later.

I also have a list of restaurants, hotels, festivals, and other diversions that are dog friendly.

Eep, I just noticed that was just one section. They have a ton of other sections for Ft. Worth and other Dallas suburbs. Maybe we should pinpoint the location first, then I can look up some places for that area.

I think I may prefer something in Ft. Worth since this will just be a day trip for me. But I'll go with the masses