I think it's corporations that have to pay tax twice, not LLC's... Or maybe I'm reading what you wrote wrong? But seriously, llc's are much easier than s or c corporations to manage, and frankly your chance of hitting the IPO lottery are pretty bad, statistically. You'll save time and money on the llc and as long as you manage things properly a decent lawyer ought to be able to switch you to c or s corp status should you hit the big time.
One other problem with a Delaware corporation, specifically, is that if you're in California, you may be subject to their tax in addition to Delaware.
Also, one other point. Investors love Delaware corporations because they know them and also because they tend to be favorable to the investor. You probably want to read that last sentence again. Also I watched a presentation by some lawyers from Reed Smith who argued That California may actually be preferable to non-investors.
But the best piece of advice I can give you is to pick one and go forward quickly without dwelling too much.
fred