It all depends on what you plan on using it for. If it's just you and a friend get the Tahoe, if you plan on driving around 3+ people and gear get the Suburban. 1500 vs 2500: if you want a cool truck that everyone compliments get the 2500, if you want a practical truck get the 1500. If you are a careful and conservative driver get the 1500, if you are buying a truck to prove to the world that you can abuse your truck until the 8.25 and 4L60E blows up and everyone to compliment you on how cool your truck is get the 2500. I have a 1500 Sub, run 37s on it with lots of fender trimming. I run the same trails that all my friends in Rubicons run but with AC and comfortable seating for 7, tow 12,000lbs occasionally and get 16.5mpg daily driving with 3.73 gears. If you already do not have a 2500 chances are that you will not need one and the 1500 will be less expensive and easier to find.
Good luck and show us pictures of your new toy.