.. wondering whats the best site to play with this balance.. or do i just need to add more to it just to be safe?
You need to forget about thinking about being safe while gambling, in fact the point of gambling is to put your money at risk in order to get a bigger reward, so if you are comfortable betting 100k satoshis then that is the amount that you should bet if you are willing to bet more then just make sure that is not going to affect you and your finances on the long run.