Just to correct you about roulette. Maximum win per field is 50 ETH, but you can win more than 50 ETH in a single round if you f.e. bet on RED + Number 23, those are two fields and your max win will be 100 ETH.
OK, I didn't find that in the FAQ, it just says you can bet between 0.0002 ETH and 70 ETH. What's the maximum for Bitcoin (just in case I ever run into it)?
5
BTC per field (or to be more accurate per single type of bet, every stack of chips you place has their own max win), at which point you can start adding corners and splits, which count towards their own limit.