Making a long trip... Advice?

I'm going to be traveling to Houston from central
Wyoming and back in the summer. Not to mention
some cruising about. A bit of info about my truck...

It's a 2005 Chevrolet Trailblazer LT. It runs the
vortec engine, 6 cylinder. It has 123,000 miles on it,
and is in very good shape. The previous owners
and I have kept very up to point on oil changes and
whatnot. Brakes are good, tires probably have
another year or so on them, and it's a very quiet
truck until you hit the gas.

As in, you can't even hear or feel the truck when
you're inside, unless you really focus on it. I'd take
that as a good sign, but I'm not too knowledgeable.

All these things being said, I'm aware it's an older
vehicle, and I'd like to know- what can I do to keep
it running well during and after the trip?

I do know people in Texas and Wyoming who can
do maintenance on the truck, but should I stop
somewhere and have anything done mid way?
Should I not worry about it until I get from point A
to point B, as long as nothing's weird?
What routine should I follow when I get gas and
check fluids?