I've tried coinbase flawlessly so far, not big purchases but your right , here in the US there are not a lot to choices to buy.
The problem I had with Gemini, I did join, but one thing is asking me for my debit/ credit card but Gemini asked for my bank user name and password! That ain't happeneing! I believe in getting a few different alt coins, I don't recommend putting anything in a storage with coinbase or anyone, buy it and move it directly to your wallet!
Unfortunately the story is correct in that the places to buy are far and few between here in the US.