Cycle NC and Bike VA are both within a long day's drive of Memphis. I think that they offer vegetarian options for participants that use their meal plans, but I personally prefer to eat out at restaurants rather than wait in long lines for the catered meals on tours. Although most cyclists camp out on these rides, there are generally plenty of nearby motels and the tour organizers will drop off your luggage at them. Make reservations at hotels as soon as possible if you sign up for a tour because they tend to fill up fast. I have camped out and stayed in hotels while riding on organized tours. Personally I prefer camping because you get more of the "experience" that way, meeting a lot of other cyclists in the campgrounds, but it can suck when the weather is bad. Both Cycle NC and Bike VA also offer the option of free "indoor camping," which is usually shared space on the floor of a high school gym or similar buildings.

If you are a regular commuter, you should have no problem riding most organized tours. Trust me, every time I ride one of these tours I talk to people who do no training beforehand and rarely ever ride their bikes -- yet they manage to ride 50-60 miles/day for the week. Likewise, you will see cyclists riding at widely varying paces. There will be avid recreational cyclists dressed in kit who ride each day as if it were a leg in a stage race, averaging 20+ mph and racing to be the first one to arrive at the next campground. There will be cyclists just out to have a good time and enjoy the scenery, averaging 8-10 mph at best. There will even be families with their kids.

However, for your own comfort and enjoyment, I would recommend training before riding a weeklong tour. Since you commute already, you should be reasonably fit. The main thing you need to work on is riding some longer distances on the weekends. Gradually build up by riding 30, 40, 50 and 60 milers in the months leading up to the ride. Although not necessary, you will find that you enjoy the tour much more if you are used to riding long distances.