I believe the I-80 - SLC then I-15 to LAS pretty much keeps you
to 9500 MSL but watch out for the MOAs around SLC.

What isn't clear is what part of the East Coast the OP is coming from.
The I-80 route is fine for the north side. But if coming from the south
part, I-10/I-20/I-40 works very well, again, with no need to go above
10.5K. Check the sectionals..