I have the Suburban and pretty much love everything about it. Get the extra length. That extra wheel base really makes the towing stress free. As to the 5.3.. It really depends on the year model. I have the first gen 5.3. I'm pulling a 5500 (dry weight, more like 6500) TT. For the most part it does a really great job of towing but, on uphills I'd like a little more power. I understand that the newer 5.3s do quite a bit better so, if you're looking for something in the latest generation (aluminum block) 5.3 you will find it a great tow vehicle. I drove some Tahoe police vehicles and I'd much rather have my suburban for RV-ing. If you can find the bigger engine in the burb or XL GET IT.