No worries bud.
There is one more thing; I'm quite a big advocate of just getting on with it too.... I've bought my bikes based upon what companies I'd like to support. So since my return to riding I've only bought Hoffman, Macneil, Standard and S&M. They've all been quite different, but I've learnt to ride them regardless. However, I now know I like 20.75" - 21", a longish rear end and a low BB height. A bit old fashioned some might say. Bit like meself...
You won't necessarily know what you like yet, but you can get a bit of a head start over us that just had to ride bikes and work it out from scratch. As a general rule of thumb, assuming you're of average height, stuff over 20.5" will suit, coupled with a 74.5 or 75 degree head angle. You can relax the head angle a bit by running a fat tyre up front and a skinny out back, that'll take some of the twitch out. It seems to me that older returnees don't like the high BBs of modern bikes, so try and get as close to 11.5" as you can. I wouldn't worry too much about the rear end length as long as it falls into average parameters as you really need to know yourself as a rider to be able to feel the difference in back ends. In my opinion of course...
So, decide on a firm you'd like to support then start checking out shapes and sizes. Under 20.5 or over 21 isn't going to suit unless you're under 5'6" or over 6', 75.5 deg headtube I can almost guarantee you'll hate too. With all that in mind, find the model that fits the bill.
One last thing; any shop that can't give you these statistics and/or competent advice doesn't deserve your money.....
