I started on a Suzuki LS650 - a 650 cc thumper ( single cylinder ) . I was still in highschool, so that was a pretty good ride as compared to what other people were driving :) Great beginner bike too. Low seat height, light.. I rode it for 6 months ( ~~~ 3000 miles ), passed my Ohio endorsement test, and got my next bike. A few things said - I think that going cruiser, and small/medium displacement would definately be the best way to start. Also the MSF course is strongly recommended - better safe than sorry, right ?
Next was a 1990 BMW K1 - I LOVE that bike, still got it i fact. If you have to ask what it is - just look at the pic. The BMW community knows it's a GEM :)
Finally after doing some 500mi days, I broke down and got myself a 2000 K1200LT-C . Basically a 740 on 2 wheels, or a Goldwing on steroids - you pick :)
All in all - make sure you get a LEARNER bike first, pass your endorsement test ( or whatever else your state/province/country requires ) and when you feel confident, get something you WANT. And remember - there are only two types of motorcyclists : the ones who went down, and the ones who will .
Paul