I had these two things happen to me on separate occasions last year. Here's what I got.

My EWR-SFO business class flight was cancelled, and I "voluntarily" accepted a Y seat on the next available flight just to get home. I called (before takeoff, but I don't think it matters when) and got a sympathetic agent who gave me a $200 ETC as compensation, and refunded me the fare difference between J & Y, using a very generous "historical Y fare" comp of ~$120. In all, I got ~$580 back on my $700 fare, plus a $200 ETC.

My bag was delayed by 48 hours on an international trip. After I got home from the trip, I called and immediately got a $200 ETC as compensation; in addition, I submitted $580 worth of expenses for reimbursement (I basically bought 3 days worth of clothes from Lululemon to hold me over). They approved a $1,000 reimbursement for some reason (I feel like they misread what I filled out in the form, but I'm not complaining), which they're going to mail me as a check. This happened over Christmas / New Years and I waited until this week to call because the hold times were crazy.

(I was worried they'd balk at reimbursing me for buying somewhat pricier clothes from Lululemon, but I feel like I actually let United off easy because I was traveling to a place with real winter, and I did not opt to buy a whole winter jacket...)

I don't think you should feel bad asking for the full $1,500 per bag; that's their written policy, and it will help deter them from doing it again. As for me, I went out of my way to get compensated because I was angry at how it ruined the start of a special trip. And, flying from SFO, there was no weather-related reason for the delay; they simply forgot to load it at SFO. But I'm satisfied with the outcome.