Thanks everyone, looks like I will go with STA Travel, they fare is around 200 bucks more expensive than UA.com, but the change fee is only 35 bucks on their "blue" fare.

If I fly over to visit, what are my chances of upgrading on an H fare, using miles. Right now, it looks like most flights are NC0? Would be during April, probably flying on a Tuesday or Wednesday.

Thanks again for the suggestions. Never knew about STA.