At the heart of Bangkok, with all department stores and convenience you may be looking for, Siam is the place for you.
Siam is what we could call the heart of Bangkok. This is where were built the two original BTS lines are joining together and major shopping centers started to develop with Siam Paragon and now many more. The National Stadium, Chulalongkorn University, Bangkok Art and Cultural Center, Siam Square, MBK all bring a lot of diversity to Siam and make it a very lively and enjoyable place to stay.
There are no condo directly around Siam as the ground is occupied by the department stores and a royal palace (not accessible to public), they are mostly hidden behind the Bangkok Art and Cultural Center on the Kasem San sois (accessed from Rama 1 road).
The prices are actually not crazy at all and this is very feasible to find an affordable condo in there, some new condos near Siam also being built. Foreigners and thai alike share this area that reveals itself to be quiet when you walk in the sois making it a great living.
It would be advised not to have to drive often or to find a way to avoid traffic jam: Siam can be a nightmare to pass through. However as you are directly in the center you can still find a way to navigate easily once you get to know the shortcuts hidden in this area. Note that there is an express way nearby but you will to catch the entrance from another location (Hua Lamphong or Petchaburi road).
If you want to use the public transportation you are in one of the most convenient place to access the BTS. Having a condo in Siam does not mean the nearest station will be Siam. Actually you will reach National Stadium BTS station quicker and it will bring you to the Siam BTS station anyway. However you can also walk a bit further and access Siam station and choose your next destination: Sukhumvit, Phahonyothin or Silom / Sathorn.
This is also possible to walk from Siam to Chitlom station using the elevated walkway, you can reach all major department stores from that path.
A condo near Siam Paragon is something many may be dreaming of. Yes you can quickly go to Siam Paragon, MBK and Siam Square and those will certainly make most of your week-ends. As mentioned you can also access Central World and many others using the elevated walkway or BTS.
Now if you focus on food or look for something cheaper, note that there is a Tesco Lotus on Rama 1 road walking on the opposite direction of Siam Paragon.
King Chulalonkorn Memorial Hospital can be accessed from Rajdamri road, you can access it by BTS reaching the Silom station which is the nearest from the hospital. You can also access Phyathai 1 hospital at BTS Phaya Thai station or Phyathai 2 (BTS Sanam Pao).
Of course there is always the international Bumrungrad hospital that can as well quickly be accessed using the BTS line and a bit of walking.
At night there are many small bars that around Siam Square and a few dancing place like CM2 in the Novotel or the Hard Rock Cafe. The Loop Italian Restaurant and Bar in MBK is one of the trendy places to try but you will surely enjoy walking the streets of Siam Square finding new picks.
Movies, bowling, shopping is next to you at MBK and Siam Paragon. If you look for some green area you should take the BTS from National Stadium to Silom station, you can then have a walk in the Lumpini Park.