Just got back from our ST John vacation and it was perfect! Flew from Philly to St Thomas, very easy flight. We arrived about a half hour early which really put us ahead of schedule. We had a group of 6 and we rented a Jeep Commander ( for all 6 of us ) from Budget at the airport. Drove over to Red Hook which took a while, St thomas is crazy! Got the car ferry and arrived in St john in no time! We stayed at Eureka villa which we rented through Caribe Havens. Nancy the manager is fantastic! Eureka was perfect for us - very affordable with great views. Nothing too fancy, no pool or anything, but it definitely fit our needs. It was on Gifft Hill, so we had a tremendous view, but next time we would prefer to stay a little closer to the North Shore beaches. One small drawback was having to drive down to Cruz Bay and fight traffic through there to get up to the beaches. That's not a complaint, just one minor drawback.
We ate in most of the nights - we had a great deck (and did I mention the view????) that we ate our dinners out on. The one night we went into town and my husband and I ate at Morgan Mangos', which was great, and the other couples ate at Lime Inn, which they raved about also. Our last night there we celebrated 420 at Skinny Legs which was so much fun! We had dinner there and listened to the band - Outside Asylum I think they were called - they were great! That was our favorite place to hang out at - we liked Skinny Leg's much better than Woody's.
We rented a charter through Ocean Runner for a whole day - this was the highlight of the trip! Captain Doug was great, he took us all over the place. We snorkeled at the Caves & Indians, and at a little bay that was around the corner from Waterlemon??? Didn't know the name of it, we saw a turtle there though that was awesome. There was a north swell up that day so Waterlemon was a bit rough to go snorkeling in, we found a calmer spot around the corner which is where we saw the turtle. The caves and indians blew us away! They were awesome, especially the Indians.
Our favorite beach was Cinnamon, although they all are spectacular. We enjoyed going later in the day when it wasn't so crowded and swimming when the sun was setting. So beautiful!

Some tips -
We had no problem with Budget, and it was so easy getting the car ferry over to St John. I was nervous about this part, but I am so glad we did it this way. Our car was $500/week and that was a 6 passenger vehicle! Saved us a ton of money.
Definitely charter a boat for the day! You definitely have to experience this - doesn't matter where you go, but there is something so cool about being out in the caribbean on a private boat with the freedom to go wherever you want. It makes you feel so alive!
Bring plenty of spending money - groceries are super expensive. Like I said, we only ate out 2 nights, so the rest of the nights we stayed in and made good dinners - mahi mahi, tilapia, kabobs. We probably spent close to $1000 on groceries, which included beer/liquor, for 6 people for the week. Overall that's not that bad, but it is an expensive island so be prepared!
Rent snorkeling equipment for the entire week - it's cheaper this way and then you can bring it with you wherever you go throughout the week. You can snorkel at basically any beach on St John, so it's good to have it in case the mood strikes you!
Be adventurous! St John is not a "sit by the pool all day" kind of island. There is too much to see and do! Experience as much as you can and enjoy every minute.
Leave your worries at home - I'll admit, I am so used to my routine at home, that it took me a few days down there to get used to NOT having a routine. I felt like I needed to plan my days before we even left for vacation! Everyone kept telling me, just relax! And I did finally, by the end of the week, haha, I definitely could've used another week down there! It felt sooooo good not to worry about this getting done or that getting done. The best advice is not to plan too much - let each day be a surprise and an adventure.
And one last piece of advice - watch out for those painkillers! Now I understand how they got their name!

We had such a great trip and this will definitely NOT be my last visit to St John!