I'm still a relative noob to EV's but I have owned one for 2.5 years and now, with the S own two. I have a few thoughts for you:
1. twin charging, even super charging is still slow compared to filling up on gas. in 2.5 years with the Leaf and even with the Tesla S, I'm willing to pay a premium to avoid any time sitting around waiting for the car to charge, this gets old, especially with a family of 4. IMHO, definitely get the twin chargers!
2. I wouldn't bother with the HPWC, it's sexy but so far it doesn't strike me as the most robust nor versatile. bottom line, when it comes to charging, reliability is the sexiest thing around! I'd highly recommend, as stated by another gentleman, the Clipper Creek CS100. an earlier version, the CS90 has been used for the Roadster Tesla highway along the west coast and all across Canada along the Sun Country highway... they are super sexy robust and reliable!
3. for those going solar, have all future additional loads accounted for when you redo your electrical panel, this is the easiest and most economical time to add to your service. we did and it made the addition of the high powered circuit relatively inexpensive!
4. highly, highly recommend assuring tripple redundancy! we have a 14/50 coming off the 125A sub panel for the Clipper creek, that way, if/when the clipper creek is down, I can plug the UMC into it and still get decent speed charging. a third option is good since, you may not know it now, but you will likely want to get rid of your other gas car shortly and want another EV and the option to plug them both in at the same time... a dedicated 20A standard outlet is even a bonus. to take it easy on the battery, I leave mine at around 50% most time and charge off of the 40A 14/50. the clipper creek is at the end of the driveway and will usually charge the Leaf. having access to faster charging helps me bring the Tesla up from 50% easily on the off chance I need more of a charge than usual quickly.
5. consider being apart of plugshare/recargo. having a 14/50 helps increase your ability to be of service to someone in a pinch, a clipper creek CS 100 is even better, allowing most EV's to charge since it's a J1772, it's the highest powered J1772 on the market. so far, I've seen charging rates of 60 mph, which seems higher than most are reporting with the HPWC. if you have some roadsters in your area and little additional infrastructure for them to rely on, consider going with a CS 90 so they can use it too... for some reason the Tesla Roadster is the only EV that can not charge on a charger that allows up to 70+ A charging rate. In any case, while I love Tesla, I very much appreciate being able to contribute to the larger EV community through plug share with a high powered J1772.