On Tuesday, December 16th, you can do IAD-BDL-IAD for $154.20 RT.
Washington (IAD) to Hartford (BDL) - Tue, Dec 16
United United 3725 Dep: 12:40PM Arr: 1:59PM 1h 19m Canadair RJ 700 Economy (N)
OPERATED BY MESA AIRLINES DBA UNITED EXPRESS
Hartford (BDL) to Washington (IAD) - Tue, Dec 16
United United 5689 Dep: 7:33PM Arr: 9:00PM 1h 27m Canadair Reg. Jet Economy (L)
OPERATED BY EXPRESSJET AIRLINES DBA UNITED EXPRESS
Cost per passenger (including taxes & fees) $154.20
Is it worth it? Having a United credit card gets you almost all of the same benefits as UA Silver. It is very unlikely that you'll hit a complimentary premier upgrade (CPU).