Going bike shopping

I'm very excited to head out and do some bike shopping. There's a fair bit of maintenance/replacement of parts needed on my current bike (20 years old, I got it in 3rd grade, it was too big for me then). So rather than drop cash on this old bike, I'm looking to buy one in the near future.

I'm looking at townie/cruiser style bikes. I plan to use the bike mainly for errands in the neighbourhood and for toodling around. I have absolutely no interest in more "serious" bikes and cycling. I just want a bike that's fun to ride and easy to get around my neighbourhood with. I've got things narrowed down as to a few models that I'd like to look at.

What I'd like to know from those with more experience bike shopping: What are key features/comparisons to make between models? On the surface, they all look adequate and able to meet my needs.

My sister bought a 3-speed Electra Townie that she enjoys. She also got a rack on the back for panniers so she can carry her laptop to the office or stop by and pick up a few groceries.

The only problem with a "low-tech" type bike is that they are heavier and are made, in my opinion, for short trips only in favorable conditions (flat, no wind, etc.) If you do look at a more serious bike you will usually get a lighter bike and actually better bike geometry that could get you interested in more serious cycling, even though it may seem less comfortable at first.

The upright cruiser-types are comfortable at first but may discourage longer distances, hillier terrain, etc.

The main thing is to get pedaling and see what happens! Have fun with your new bike.