My thinking pretty much aligns with yours
I once felt we needed to draft a DT with our #2 to replace Brockers, but now I feel an OC is an absolute must for our first pick. Build the line from the inside out. I don't think Allen, Blythe or Corbett are the guy. I do like Corbett as our LG because that's a position where you can save a little money. Also he came mid-year from a disfunctional organization. If given a chance I think he'll more than suffice.
Without being a draft expert like many on this list I can't name names, but I think we should be able to get one of the top 3 OC's at our first pick. I can't see anyone past there being an upgrade from Allen..
As for the OT positions, let's hope the best man wins. I'd like to see Whit return for another year, but I'm not going to stump for him either.