I'd...
- Can Keating, or maybe make him a nurse. Cast a badass martial artist Asian dude as security chief.
- Can Montgomery, and hire an African, or someone who can do a flawless, reasonably thick African accent.
- Retain Polly, but keep her in standard Vulcan garb, and not in the chain of command - have the pilot be first officer.
- Terminate the TCW, but make the series a parallel universe show (not a XI-like altered timeline).
... The ultimate thing is, though, that the very concept of Enterprise as a show thrusts into the forefront the paradox at the heart of Trek, namely: why are humans so special/so central to the UFP? Dozens if not hundreds of other species have been warping around for centuries more. I've never quite figured it out, and have always thought it best to ignore the question, much as one ignores why Star Warsians speak English (/"Basic"), a combination of Latin and Germanic languages. Not sure whether this question should be addressed, or ignored further.
One more idea for y'all:
- Split the premiere into two parts: the first hour a real-time action ep, a la 24 but with transporters and such, and the second a repair-based ep that flashes back to the lighter times of assembling the crew (see: West Wing's "In the Shadow of Two Gunmen").