I was assuming you're just talking about running your tank, so...
It's all going to depend on how long that cord has to be to get from the generator to the tank. You'll need a good, three wire (grounded) cord no matter what. It will also depend on what you plan on running; but as a general rule I'd say, 14/3 cord for 25', 12/3 cord for 50', and 10/3 cord for 100'. (The first number is the gauge of the wire, the second is the number of wires in the cord, that's how they'll be labeled.) As long as the cord is big enough to handle the load, there's no problem plugging in a power strip.
Oh, and just so you know, a good, 10/3 100 foot cord (if that's what you end up needing) will be over $100
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