We are building a 3-season timberframe porch using red oak (felled from our own yard).

Can anyone recommend a good finish for the wood?

We have used Sikkens Cetol 1-2-3 with good results. It leaves a fairly glossy finish but has not greyed or peeled in two years. Also Landark now has an exterior all-natural finish available. Landark is in the resource guide and Sikkens products can be found at your better paint stores.