Welcome to the forums. Some good advice here already. I'll add just a few things. First, if you go the route of riding what you have and taking your time to sort things out, you may want to get the bikes checked over at a shop to make sure everything is running OK. In response to your comment about not knowing Shimano from Sun Tour, almost all of today's equipment is functional at a level we could only dream about 25 years ago. Finally, in addition to shopping for bikes, you should be thinking about shopping for the bike shop as equally important. Sales people who listen instead of pushing their agenda are worth their weight in gold. With that said, sometimes shop personnel can be good listeners if you make it clear that you want them to be so. My favorite shop was not so in the beginning. It wasn't until I said, "Look I don't need you to sell me on something. I need you to listen very closely to the questions I have before answering." This go the shop owner's attention, and he same out onto the floor and, along with the sales person, walked me through options based on my questions. Bike shops operate on a pretty thin profit margin, and if they see you as a potential long term customer, they should be working to hear what you say, and not pushing product. If they don't, perhaps you need to find another shop. In my area there are several bike shops that allow folks to rent bikes. This is one way to get a bit of a longer demo period on different styles of bikes before buying.

Regardless of which direction you go right now, enjoy the ride!