In reply to konanm:
Apologies for the tone of my earlier post. I thnk what surprised me was how a bunch of 6a/b+ sport climbers had got that far (assuming you mean that you can lead those grades on real rock) without picking up a bit of info on abseiling etc. Because, to be honest, that's your only issue here.
Climbing a long sports route may feel more committing, and I suppose it is, but other than having the desire to keep on pushing when the going gets tough (and it may if you've picked a route with a lot of pitches at your limit) it isn't difficult in terms of skills. You very rarely get stopped completely on a sports route (unless you are really pushing the boat out) and can normally frig your way up it if needs be or lower back down to the last stance. The obvious thing is to pick a relatively easy route for your 1st multi-pitch route so that there's little doubt you can climb it and you can focus on the rest.
Just about the only thing you will really need be sure about is your ability to abseil back down the route; either to descend or to escape. I suppose abseiling off long routes is an acquired art as there is more to go wrong and it can be worrying (particularly if you aren't sure where each abseil station is). On a sports route you will often abseil straight back down the line, re-forming your abseil station at each belay. Each belay should have something like a couple of ring bolts, or a big door knocker, or a couple of bolts joined with a maillon. You will either thread the rounded ring bolts directly or use the maillon. As you go up you need to be making a mental note of where the belays are so that you have a better chance of spotting them as you come down the route without over shooting. If the abseil descent is off to one side (not uncommon) the topo will normally show it and you may also want to see if you can spot the ab stations as you go up (or watch others coming down it!).
If you haven't abseiled before and learnt how to tie an abseil knot (if you will be climbing with two ropes rather than one very long rope which you can just abseil off the middle of), you need to learn. You will also need to learn how to use a prussik to provide a safety back-up. Safety is paramount and ideally you should work as a team, becoming more efficient and competent each time. One technique is to set up the 1st abseil, all get onto it in a 'stack' (one person above the other), and then the lead person abs down to the next stance (and makes himself safe at it with say a cows tail attached to the bolts there before takiing himself off the rope) shouts up that he's off the rope and is followed by the next. That way you've all checked that you are properly on the rope before you set off. The 1st one down each time will often need to sort the ropes as he goes (one reason why a back up prussik is a very good idea) and has to be careful not to overshoot the belay - it's a real pain trying to get back up if you suddenly realise it was 20ft higher up!
There are also things like tieing stopper knots in the end of the ropes to stop yourself abseiling off the ends into free air! It does happen, unfortunately. One trick I learnt early on was for the 1st one down at each stance to undo the stopper knots on the end of the ropes and thread one end of the rope through the belay bolts in preparation to then pull the ropes. Unless you are abseiling off one long rope, you need to remember which of the two joined ropes you are going to pull (hence having different coloured ropes helps) - this will be the one dangling on the side with the joining knot (so you aren't trying to pull the joining knot through the maillon or ring bolts at the top). Then as one of you pulls the rope to retrieve them, the other pulls the end of the rope through the bolts near you at your new stance. When they come free, you are most of the way to being set up for your next abseil. It also ensures you don't drop the ropes!
Steeper abseils tend to be easier in terms of rope management (even though it seems scarier) as the ropes tend to hang free and tangle less. However, it does tend to be less forgiving in some other respects. Slabs will tend to grab your ropes and tangle them up, as will bushes/trees on the route. However, it's probably a little less worrying for your 1st abseils if you can do it on slabs.
Don't ever forget to untie the knot on your end of the rope when you pull the abseil ropes though. Leave one in the end and it will jam at the top and leave you in a right pickle. Of course, ropes are perverse things and can tangle anyway and jam an abseil. To illustrate Offwidth's point about me being dismissive, one very memorable experience was having an abseil rope jam high up on a 16 pitch route in the alps, when the heavens opened and I had no choice but to re-climb the entire pitch (6a granite slabs in the pouring rain...) on the end of the free rope. We then had to complete the 16 abseils, each of almost 50m, with sodden ropes and lightening starting to flicker around us. Keeping your cool in such situations is important. One f*ck up and your parents might get an unpleasant phone call. So, maybe also check the weather forecast and conditions before setting off on a long route!
It's all a lot easier than it sounds in reality. As I said, start on routes which you know you can get up so you can focus on a) getting up ok, and b) spotting how you will descend the 1st time. Don't be too ambitious and you will learn from experience.