SMART statistics are just index numbers. The drive doesn't actually tell the computer "flying head time is too long", it just spits out some numbers -- a test number, a value, and the acceptable ranges(so your program doesn't have to know what it is to know it's bad). So, whatever test number "flying head hours" is may mean something totally different for your SSD. Look up the manual for your drive or ask the manufacturer.
I reccomend ext4 over ext3 for heavy-duty things since it's faster for large partitions (ever tried to fsck a 100GB ext3 partition? Takes a while). Also, it can be defragmented
without unmounting it, which could end up being very important for the long-term performance of your virtual machines.
Otherwise, making a filesystem work well with an ssd is mostly about fine-tuning it to match its block sizes and boundaries. If you get it wrong, it won't explode, but performance might be just slightly worse. See
SSD - Gentoo Wiki for some general advice.
Also, an
fstrim once in a while is good for the SSD, it helps wear-levelling work better by informing the SSD which blocks it doesn't have to care about anymore. See the wiki again for that.