Utah fishing in February

I'm looking for some advice for fishing in February in Utah. I have one day
to fish while I'm there and am trying to nail down some plans.

The Green River or the Provo? If the Green, section A, B or C and if the
Provo, the Upper, Middle or Lower?
I'll be wading with no access/no desire for any pontoons or such. I'm also
heavily leaning towards the Provo for it's proximity to SLC. I understand
there's limited access to the Upper, but I wonder how much of that is meant
to funnel traffic to the local guides?

Any suggestions on flies? I'm specifically interested in not only the
pattern and size, but the color.

If anyone is interested in meeting up, I'm looking at Feb 12th. I will have
one, potentially two, friends with me that haven't fly fished before (it
could be somewhat ugly, but I've got them headed towards their local fly
shops and libraries for books and instruction) but someone at a flyshop (the
Four Seasons) suggested the Lower Provo and said it was pretty densely
populated with fish and that there'd be plenty of space/holes for fish, so
maybe it won't be too crowded...?. I've certainly seen more than that at
Penn's and local streams here...