I think Rendezvous is worth it for the experience, especially if you want to be downtown. Try more than just the pork ribs though - lamb riblets, sausage plate, the red beans and rice are pretty good if they are serving them.
On Beale St proper, Blues City Cafe is decent for ribs, and Dyer's is famous for their grease cooked burgers!!
Payne's is not close.
I decided to try Rendezvous just last week. While they weren't the best ribs in Memphis by any stretch, they were still pretty damn good- better than you can get in just about any other city! I was kind of surprised after reading all of the negative stuff on here, but I would go back in a heartbeat. I sat at the downstairs bar- service was friendly and fast, and the people on both sides of me actually lived in Germantown, so if that makes it a tourist joint, then that is ok with me...Rendezvous is one of those places that people actually travel to get to- I don't think that being a tourist place in this case is really a bad thing at all...
Rendezvous has always been a good experience and good food when I have gone. So good IMO that while livng in California I would have them shipped in for parties. They are just off Beale Street so they are close to where you will be. Just know going in that they are the best DRY ribs in town. The best WET ribs I think are at Central BBQ (Not that close to Beale but not to far of a drive or cab ride) For pulled shoulder I like Germantown Commissary or Central or Corky's
I have been to Rendezvous about 10 times over the last 20 years, and based on my experiences, there has definitely been a decline in overall quality of the barbecue. Last time I was there (about 2 months ago), the ribs were nowhere near what I'd consider the best that Memphis has to offer - they were lukewarm, tough and undercooked, and as always...very expensive.
HAVING SAID THAT...I do still love the atmosphere at Rendezvous, and I suppose it is one of those places that you "have to visit". Just know that there is much better BBQ to be found in West TN/Memphis. Maybe a trip to Rendezvous will whet your appetite to seach out the good stuff next time.