I've gone to the SPG Suite for the past 4 years and going again this year.
Yes the suite is shared. I believe (depending on who shows up) there would be about around 12-14 other people there + 2 or 3 from SPG / IMG (contract workers for food/bev).
The suite (110) is right at dead center court and the views are great. I have not used the SPG courtside seats yet. Arthur Ashe marks the entire lower seats section as "courtside". But SPG's seats are in row C, which is still really amazing seats.
For the same price in points I chose the suite because of (a) unlimited food/booze, (b) ability to move around, get up stretch legs, etc., and (c) coverage for sun.
If it rains matches are stopped so that doesn't really matter.
Back in 2011, the first year they offered, the suite tickets (for flat rate redemption) were 35k points. 2012 and 2013 were also 35k. Last year (2014) they jumped to 45k. Now this year up to 50k.
As far as dropping in value, I've never seen them drop the prices when it looked like there was still options available. But you never know.
View of court from the suite:
View of court from courtside seats (not the SPG ones, those are on other side, but view is similar). These were from row B:
Any other Qs, let me know.