Well Jared, I've been meaning to post some sort of review of the iPhone 3G, having just upgraded from the 2G model a few days ago. Here are some things you may want to consider.
The iPhone 3G is certainly a wonderful addition to Apple's line of already strong products. Knowing that, you can't go wrong with an iPhone (either the 2G or the 3G.) It is easily the most functional and intuitive hand held device on the market today, and it blows all of it's so-called competition out of the water in terms of performance, reliability, ease of use, and the quality of the overall user experience. Since you're already a die-hard mac user, you already know what I'm talking about to some extent. Just imagine having OS X in the palm of your hand. Literally.
Okay, let's get down to business.
The iPhone 2G has basically everything the 3G has. Same screen, same accelerometer, same processor etc. The 3G adds GPS functionality, clearer speakers, a sleeker back and yes, 3G HSDPA capability. Keep in mind that the "twice as fast" thing is more of a marketing ploy than anything else, as MANY people seeking the iPhone 3G may not actually live in a 3G coverage area (myself included - but I did my research so I wasn't surprised like so many other people are.) You're from Jacksonville, Florida, so according to AT&T's 3G Data Coverage Map, you're set. The 3G voice quality is noticeably clearer than 2G voice quality (you can turn 3G off on the iPhone 3G to increase talk time and usage - and in some cases get better signal quality - see below)
The drawbacks that I have experienced with the 3G are minor. Certainly not anything to make me tell you NOT to get one, but they're definitely things you should keep in mind:
1.) 3G vs. 2G signal quality will obviously vary from location to location. However, many people in 3G coverage areas (I've been in a few recently with my new phone and have experienced the following myself) report that the 3G signal quality tends to be weaker in many areas than the 2G signal quality. So basically, if you turn 3G off you actually get more bars in some (many) areas.
2.) 3G vs. 2G voice quality is noticeably different, as the 3G network supports a higher quality audio codec than AT&T's standard network. The voice quality in 2G is still very good, and it's just something you'll want to test on your own to see what you like best.
3.) Most importantly, keep in mind that having 3G turned on will drain the battery much quicker than when you have it off. There is a setting where you can turn 3G off (the phone will then be on the standard GSM network with the somewhat slower EDGE data connection) and you'll notice much better battery life.
4.) As far as battery life is concerned, I have yet to do any serious side-by-side testing between the iPhone 3G and the iPhone 2G. However, I have noticed that my battery seems to be a bit shorter lived in the 3G. Now, keep in mind that this could be for a NUMBER of reasons. I am just finding out about all of the new and exciting applications available in software 2.0 so I have been using my phone a lot more. I think that's partially to blame. However, I used to do a LOT of web browsing on my iPhone 2G and rarely saw my battery go below 1/3 power at the end of the day.
KEEP IN MIND that you will use the HELL out of your iPhone when you get it. You will be so stoked to play with all of the nifty features and applications that you will crap your battery out faster than you can imagine. This is okay. I promise, the battery life is much better as you start to use the phone at a more "normal" pace. That will probably take a few weeks.... so just have fun with it and don't worry!
5.) The iPhone 3G feels better in your hand than the 2G. The 2G is still a very comfortable phone, but the 3G's thinner edges make for a much more comfortable feel. The aluminum back on the 2G is very susceptible to scratches, DENTS and scuffs. The 3G's polycarbonate back is actually very durable and although I have not tested it's drop damage resistance, I think it will actually do a bit better in terms of not denting like the aluminum back of the iPhone 2G. The black polycarbonate on the 8gb 3G and the 16gb black 3G model certainly collect fingerprints and tend to look dirtier than the white 16gb 3G. I opted for the 16gb white and have been very happy with it.
As far as protecting your phone, I HIGHLY recommend that you get a case/protector for it. Being the minimalist that I am, I swore by the Incase rubber protective cover for my iPhone 2G and I intend to buy one soon for my 3G (
Click here for the Incase rubber cover for the 3G!) The Incase covers are very unobtrusive, and they protect the sides, back, buttons and corners of your iPhone. The drop resistance is INCREDIBLE. I saw my friend drop his 2G a number of times with the Incase sleeve (on tile, pavement, hardwood floors...) and that's what prompted me to buy mine. They also make the phone a bit more comfortable to hold (at least for people with larger hands) and they also prevent the phone from sliding around, since the back of the protector is nice, grippy rubber. I tend to lay my phone on my thigh while driving and talking on my Jawbone, and the case keeps the phone from sliding off into the abyss between my seats and center console.
As you can see, the Incase rubber sleeve adds very little bulk to the phone. Other cases just don't compare.

Alright, so I know this is getting a bit long but there's one more thing I want you to know about protecting your iPhone. People will argue that since the screen is glass it is very hard to scratch. Yes, that's true, but why risk it?
The Power Support Crystal Film Set is an absolute MUST HAVE. It adds a beautifully invisible and durable "adhesive" film to your iPhone's screen, which will protect it from skin grease, scratches, minor dings and other elements. For $14.95, you get two of the films, each of which will last 3-6 months depending on how anal you are about how your screen looks. They don't come off under use, they don't degrade the screen quality AT ALL (keep in mind I said they're invisible - they really are, except for being able to see the slight edges of the film) and they don't degrade the multi-touch sensitivity of the phone either.

So there you have it. My not-even-complete review/comparison/suggestion list for the iPhone(s)
As always, if you have any questions, feel free to let me know. Being as it's 1:05am I'm sure there's something I left out.
Enjoy your new iPhone!!