So guess what... Part of my job is running a digital studio, where I have a staff of graphic artists, art directors and... photographers. I deal with this day in and day out... But of course you're talking personal-level stuff: Even so, since it's part of my job, I've got a lot of personal experience too: I've used digital cameras since the dawn of time (okay, since the early 90's when they still used floppy disks)... I have about 21,000 digital photos stored and have made well over 1,000 of them into prints... Not bragging, just pointing out that I know what I'm talking about here (more than I can usually say on the Gauge!)
Having used them for years, I second the vote for Nikon for a good general-purpose camera that will do about everything you want unless you go "pro". I have a 4300 (4 megapixel) and have blown photos up to 11x14 with superb clarity. 16x20's are just a hair less clear than a "real" photo, but unless you're really looking for it AND you've recently dusted AND windexed a framed 16x20, you can't see the diff... and really - how many 16x20's do you plan to make?
Also, I would advise AGAINST buying a printer with the intention of printing your photos. Either you're buying an inkjet printer, and no matter what any manufacturer says or what special paper you use, they will look rotten. OR, you're buying a dye-sublimation printer, which will produce photo-like output, but they usually only do it in one size (like 4x6 or maybe up to 8x10), they cost a lot, and MOST importantly, the cost of dye and paper will actually run you more per print than doing it at the drugstore.
The drugstore? Yes, many chain drugstores (CVS around here) have machines into which you put your card and get 4x6 prints spit out. About $0.25-$0.30 per print, which is comparable to film develop/print costs (especially when you factor in that you can preview and simply not print pictures you don't want). You can even stand there 10-15 minutes while the machine does it for "grab & go" service. I understand some of the club stores (Costco, etc.) also have this and charge slightly less, but you can't wait for them, you have to come back later.
For the general stuff, you've already got good advice. Things I'll "thumbs up" from my experience.
BUY A LARGE CAPACITY CARD. The ones that come with the camera are small and usually hold 20-ish pictures. That is definitely not enough. I would advise you to buy ONE LARGE capacity card rather than several smaller/medium capacity cards. Think in film terms - would you rather have one roll of 200 shots, or 4 rolls of 50 shots each? It's just a convenience thing. Usually the cost factor is irrelevant - or actually in favor of one bigger card.
Extra battery is definitely apropos.
Don't buy a camera that only runs off alkaline batteries (pretty hard to do nowadays anyway). If you buy one that comes for use with alkalines, but sells rechargeables as an option, get them -- two sets.
Make sure it has a good macro function - Model RR work requires it, absolutely.
Digital zoom is near worthless. Don't even pay attention to it. The optical zoom is what matters.
Best of luck!