When people refer to places near Cruz Bay, they're often not referring to being in Cruz Bay itself. More like the western side of the island, although there are places to rent right in Cruz Bay. Here's a link to a useful map:

http://www.virgin.islands.national-park.com/map.htm

As you see, there's a lot of area to the south and west of Cruz Bay where villas can be rented. They're a distance from Cruz Bay, but much more convenient than if you're over on the Coral Bay/East End side.

Coral Bay is more spread out, is more laid back, has fewer restaurants/bars/markets. Cruz Bay is a much busier place, has many more restaurant options, markets, shops. If it seems like you'd be going into Cruz Bay frequently, I'd suggest staying on the Cruz Bay side (but not necessarily in the town itself). We like the Coral Bay/East End side and really have little to do with Cruz Bay.

Last year, we stayed at Cruz Bay Villas just up the hill from Cruz Bay (Woody's, Quiet Mon, etc). While there is traffic around that area into the evening, it was totally quiet as close as just "up the hill". We're staying there again this year because we really enjoy the north shore beaches (Cinnamon, Waterlemon) and the convenience of the restaurants in Cruz Bay. We don't stay out late, but after a great day at the beach and some time at the condo to shower, change, pre-dinner cocktail we like to have a liesurely dinner and after-dinner drinks. By that time, it's 9:30 and time to go back.

Never stayed out at Coral Bay area. Did drive over there last year and it looks great. I will definately plan a stay out there in the future to experience that side of the island. Many great times reported at the beaches and beach bars/restaurants.

Either way - you'll have a blast!

Good Luck! Have Fun!

Everything is relative...
Cruz Bay is not loud relative to Charlotte Amalie on STT and most anywhere else in the free world where more than 500 people congregate. Cruz Bay is loud relative to Coral Bay and my immediate neighborhood. That said, as VI Lover mentioned, it won;t keep you up at night if you live just up the hill.
Parking can be more of an issue during the high season than the summer but one can always find a space although you might not be able to park immediately in the area you are interested in.
The island is small and even though the roads are not expressways, it doesn't take more than 30-40 minutes to get anywhere from anywhere. We stay on the SW side of the island as it is less congested with villas but close enough to Cruz Bay [10 minutes] or North Shore beaches [15-20 minutes] for convenience.
The only issue I would consider if you might want to enjoy Cruz Bay after dark, is the drive back to Coral Bay should be taken with plenty of time on hand and not plenty of drink. The roads are not bad but they do need concentration, especially at night.

I think it depends on what you are really in to. If you want to be relatively isolated and not worry if you are dressed when you step out on the deck or porch (i.e. no other houses in sight), you would probably like the Coral Bay side of the island. If you want to be able to go to a number of different restaurants for meals, Cruz Bay might be more to your liking. Either way, you are going to have a great time! As Chris said, Cruz Bay is not loud or big relative to most places; but it is compared to Coral Bay.

It's a matter of preference....if you want night life, and want to be able to bar hop and enjoy yourself at night with several other people I'd say stay in the Cruz Bay area. If you want immediate access to shops, restaurants, banks, stores then Cruz Bay is for you. If you want to get away from the more crowded life of Cruz Bay then head to the other side of the island and stay in the Coral Bay area. Coral Bay is fantastic....there's bar/restaurants to frequent, there's several great shops to hit but it's not area condusive to walking from bar to bar, you definately have to have a vehicle. If you are into partying and hitting lots of local spots then I'd say stay in Cruz Bay, you absolutely don't want to be driving from Cruz Bay to Coral Bay after a day/night of drinking. The roads are way to windy and dark to risk the trip. We love the Coral Bay side of the island, we rent a villa that's private and all our own. During the day we head out to the different beaches, restaurants etc. and then head back to the villa, shower, unwind and head back out to a local restaurant for dinner then back to villa for a night of relaxing in the hot tub and then to bed. It's all up to what kind of "social" life you want during your vacation. Cruz Bay to Coral Bay is probably a good 30-40 minute drive, not something I recommend at night but we often hit a few beaches somewhere between Coral and Cruz during the day, stop in Cruz Bay for an afternoon cocktail and possibly a few necessities at the market, then head back to Coral Bay in the daylight. The island may only be 9 (?) miles long but it takes quite awhile to get from one bay to the other.
So whatever you are looking for be it nightlife within walking distance or a quiet tranquil retreat both are available on St. John but not necessarily side by side. Enjoy whatever it is you decide and have a safe fantastic trip.

One more IMPORTANT thing not mentioned is the breeze. Coral Bay has MUCH better breezes and I find it to be much more comfortable.