Depending on the implant you choose as well, korea brands much cheaper starting from 30,000 Baht. I use straumann at government dental hospital cost me just a little under 60,000 Baht from the estimate of 80,000 Baht [ but I didnt need gum or bone graft ]
Don't commit to one or two gyms and prepaid. Try them out and choose the gym/trainers that you like or find helping you to achieve your goal. There is no one gym fit all. Try and see which one you love.
Silom will be just hectic like khao san area ONLY more expensive, same as Sukhumvit early soi, Siam. Sathon went there last week not much going on in the evening but you can always take BTS to places. I work near khao san road and just wondering if you try to stay elsewhere further away from khao san but nice and quiet at night ? Perhaps Sam sen road area etc.