Rainbow wall is ridiculously well protected with a ridiculously small rack. I've been on the wall 3 times now, heart and the rack has shrunk each time. There is great gear, ophthalmologist the crack changes sizes, and there are bolts protecting many of the cruxes. I would recommend taking the following rack.
0-3 Metolius TCUs, doubles in the 1 & 2
1 Set of nuts, small to medium
1 60m rope (a 2nd is optional for hauling or faster retreat)
The rack is the same for the Original Route and Rainbow Country. This rack will allow a 5.11 climber to french free the Original Route and get down. My first time on the wall, I did just that and went 13 hours car to car. It was awesome. This is one of the best routes in the US Southwest and I highly recommend it. It is safe, fun, and non-commital since you can bail so easily, carry so little, and pull on gear to get through cruxes trivially. The wall get a lot of shade, facing mostly north, so you don't need as much water as some other long routes in Red Rocks.
While rappeling this thing with a single 60m is safe and easy, I find that bringing a tagline allows two things:
1. I can rappel much faster. One 200' rappel seems to equal 3 rappels with a single 60m rope multiple times. You can get down from the summit in about 6 rappels.
2. I prefer to haul a pack and let my follower have the chance to enjoy themselves on the free climbing. While this slows things down a little, I feel that everyone has more fun. The hauling is trivially accomplished with a 8mm tagline by hand (tibloc on a carabiner optional), and the faster rappeling makes up for some of the time lost.
Many pitches can be linked on this, since they are essentially all under 100'. In fact, almost any two pitches under 5.11+ can be linked on this route, and amazingly enough the tiny rack is enough to link if you know what you're doing.
I hope that helped, now get it done!
(For more approach and rappelling beta click here: Luke did a writeup in his blog from when he and Roberto were up there a few weekends ago)