Just remember that the status match is likely a one-time only thing. I am NW SE and UA 1P, both earned the hard way (well double miles helped me out w/ NW last year). Having status on 2 airlines is awesome, but if I were you, I'd shoot for the higest possible status on the airline where I do the bulk of my flying (for me, UA). The treatment of low-level status vs. high-level status is more or less the same, IMHO, minus the upgrade possibilities (which I suppose is the biggest perk for most. for me, it's getting 3timesacarryon onto the plane with me ).

So I would make the decision based on the bonus miles that I'd be accruing. The difference between 1P and 2P on UA is pretty big (i.e., 25% bonus miles vs. 100% bonus miles). Conversely, the difference between GE and PE on NW is small (125% vs 100%).

You can set up some kind of break-even equation to determine the milage you'd have to fly on UA vs. NW to make mid-level status worthwhile. And actually, since i am the kind of dork who enjoys nothing more than setting up spreadsheets on the weekend, I did this just now for fun.

According to my calcs, if the OP does > 75% of flights on NW, then going for the PE/2p status combo is better than GE/1p. at 75% it's a wash, and below that, GE/1p is the winner.

Again, this is based purely on RDM. So it doesn't take into account the fact that UA peeps have to apply for upgrades while NW peeps get them for free. And then there is that 1000 mile bonus for riding in the back of the bus and all of that. Once you factor those in, then NW would have the upper hand at a (perhaps much) lower flight threshold.

this probably makes no sense, right?

Edited to add: just realized that we are talking about PE vs. GE/2p. At that point you'd need to fly more than 50% of flights on UA for the RDMs to work out in favor of GE/2p. And since upgrades are nearly impossible (in my past experience) to get as a 2p, I think the choice is then clear.