i think they should have the option to straddle, like a button to check off, straddle next hand. Asking every person that is UTG if they wanna straddle would take too long.
They could possibly make it a fixed check box below/next to
[ ] Sit Out Next Hand
[ ] Auto Post Blinds
[ ] Straddle UTG (or) [ ] Straddle When Ready (or) [ ] Post Straddle Blind
^^ This would auto post your straddle on the next available hand, and you could click it off/on as desired.
As for Check/Bet dark, this could/would delay games I think. Especially when it goes heads up, or even just 3 or 4 to act. I guess the option could appear in the 3-7 seconds while the other player(s) are acting and then automatically disappear if you don't check it in time. In a live game you have the few seconds it takes for the dealer to deal. In an online game you have... no time for the dealer to deal