If you must stick to US for some reason then you might also consider using BD (BMI). Pretty easy to attain *G and then even easier to maintain it from there out. Foreign *G will also get you lounge access in the US, though no free upgrades on US or UA.

If you have a non-US and non-French address then AF Flying Blue may be a great deal for you. You'd get lounge access as an elite plus and also free upgrades on NW. (I say non-French address because members in France are penalized with a higher threashold for Gold and Platinum)