It is easier to manage space on any drive if all of the space is available to be reused.
If you divide the space up into two or more partitions, then some will fill up prematurely.
There is no performance advantage in partitioning.
geofelt is entirely correct, However I do partition my 258 gig SSD, for the following reason.
1) I set the C drive to say 100 gigs. I can then use windows Backup to back up the system drive (image) that can be installed to any 120 or 128 gig SSD.
2) I'm NOT a gamer so do Not need even the full 100 gigs for OS + programs.
3) I use the remainder of the drive for my data - simplifies Back up. Never did like combining OS + Programs with data I generate.
Laptop: 256 gig 840 Pro SSD = "C" (100 gigs) and "E" (remainder), have not gotten around to switching Drive letters. 2nd SSD 256 gig M4 - drive D, only the one partition.
If this is a Gaming system do as Geofelt indicated, and you anticipate using upto 180 gigs. Remember you lose some do to the way manufactures count (Not to smart so they have to use all ten fingers vs a computer using just two digits), then you MUST leave min 15%, recommend 20%, unused so that wearleveling, garbage collector, and trim can work their magic.