I would bump up the fee a bit for a big gig. Not ridiculously so, but if it's a big budget gig you need to put on a good show so you might be rehearsing extra thoroughly; you'd definitely need deps if someone was ill or whatever; any faintly dodgy bits of equipment will want to be replaced, even if it's only crackly leads or whatever. Ultimately, the fee any musician gets paid is not about how awesome they are, it's about how much money is changing hands for the event. Even if people are not there just to see you, you're contributing to a big piece of business; you will want to behave extra-professionally in that context, but you also ought to get paid a little bit more.