Originally Posted by bgriff

That does complicate matters a little bit. On UA you'd have to use RPUs to upgrade those flights. On DL in theory you'd be eligible for complimentary upgrades, but in practice you'd probably need to use RUCs on that route most of the time or your upgrade wouldn't clear (and even with RUCs, at peak business travel times of week you may still not get the upgrade, though that's probably true on UA as well).

How you earn RPUs and RUCs is slightly different between the two airlines ... on UA in theory you can earn lots of them if you fly a ton each year (IIRC I think you get 2 at 75K miles and 2 more for every 25K after that? Or something like that). On DL you can earn 4 at 75K miles/Platinum, and 8 more at 125K miles/Diamond, but no more than that. And on DL those RUCs are part of the choice benefit program, meaning you have to give up something else to get RUCs -- most notably, at the Diamond level, you can only choose either 8 RUCs or 4 Global Upgrade Certificates (which would most likely be useful to upgrade personal travel, given your business travel patterns), but not both. Though to be fair, other than having to choose between RUCs and GUCs at the Diamond level, the other options for your Choice Benefits are mostly things like bonus miles or gifting status that UA doesn't offer at all, so you're not missing out relative to what other airlines offer, you're just creating an opportunity cost decision for yourself.