I much prefer EWR to IAD anyday.

My UA hub preference: CLE (best), EWR, ORD, DEN, SFO, IAH, IAD (just awful)

My least favorite airports in the whole US: LGA and JFK.

First: never find your flights at united.com, use matrix.itasoftware.com to find the best fare/routing then go to united.com or other website to book it.

When using united.com set results to 50 (from default). Putting a preferred departure time can also be helpful in some markets.