I hope when you say the delta, you mean some of the sloughs further towards clifton court and not say, franks tract or discovery bay. When current/wind rips there , it's barely fit for small bass boats let alone tubers. Let's not even start with all the tournaments/bass boat traffic over there too.
If anything, start with the smaller ebmud pay to play lakes like shadowcliffs, del valle and lafayette and maybe even coyote. A lot of lakes are doing inspections for the quagga so as tubers, we actually get scrutinized a bit more. If you get more players, I say berryessa, solano and clear lake. The wild card will be sonoma due to issues of low water currently (but seriously, which lake doesn't have it this year?). best of luck and keep us posted