In an insta-company there's no working your way up the ladder. For each executive assistant sought, a corresponding executive must also be recruited. Save yourself the stress and aggravation that comes with true responsibility and go for the job with the two-comma salary.
Startups are all about the future.
You'll need them. The dot-com dress code calls for beltware, not neckwear. After all, this may likely be the first time the person sitting across from you has conducted an interview. He's just as panicked as you - probably more so, since he's supposed to know what the job description means. You may be asked technical questions or brainteasers involving manhole covers or the number of hookers in Chicago.