I've been stuck twice at EWR. CO put me up at HoJo and UA out me up at Ramada. The HoJo makes the Ramada look like the Taj Mahal. I thought Ramada was more than adequate for for a night. There were also a number of crews there.

Oh, I do not think that UA and Chase will coordinate in any way. My experience with Chase is that their insurance programs attempt to find any way possible to deny a claim. I have personal experience with this (not a travel claim). So, if it is a mechanical delay do they just automatically deny since they know UA will pay under those conditions? Any real experience out there?

I was given a voucher to the Ramada Inn once myself, for a two-night stayover due to weather at IAH delaying all flights in the summer. I took the voucher, and immediately booked two nights downtown at the W.

Was sent to Wyndham Garden Inn. It was okay except for the evacuation due to a smoke alarm at 4 am.

I too would be interested if they deny when they know it was a mechanical and you got something from the airline.
When we had a mechanical a few weeks ago leaving EDI I rebooked on the phone and found my own hotel to avoid the massive line at the airport.
I thought about claiming the hotel on my Chase Reserve insurance. When you fill in the form online it asks how much the airline gave you - I felt bad admitting that United had already shelled out vouchers for $1200 ($900 EC 261 + a $300 "we're sorry" voucher) so I abandoned the claim. It was only $100 and couldn't be bothered with trying to explain why I didn't wait for United's accommodation offer, supplying documentation etc.
If it wasn't for the EC261 comp I would probably have followed through (or if I didn't find a last minute rate at a decent Hilton).

I had a flight to Austin suffer rolling delays and finally cancel due to mechanical. Rebooked for first thing the next morning and was given a voucher for the Doubletree airport hotel.

First, either maintain comprehensive travel insurance which includes a broad "interruption" provision or be prepared to pay this out of pocket every once in a while. Travel insurance is pretty cheap and there are many other features of most policies which make it worthwhile. Be certain to read the policy language itself, do not rely on the marketing stuff and certainly not what any phone agent tells you. While there is no coordination on benefits, most policies contain a provision which permits the insurance carrier to require you to provide a letter from your air carrier providing that certain benefits were not provided and were not offered and declined. Air carriers generate those on requests on demand. You will find that these are most often requested for flights covered by EC 261/2004 where the carrier has a "duty of care."

Second, if you call a property directly (not the toll-free or local reservations line) and it is late enough and there is availability, you may find some very good rates as an on-duty manager has every incentive to get rid of rooms he won't otherwise sell. Consider whether you want the Marriott at a deep discount (no benefits/perks) vs. some dump for free (voucher).

I've used the Chase travel insurance at least twice during mechanical cancellations. I can't remember what the terms say, but it was relatively painless - as far as filing an insurance claim goes. I honestly didn't check to see if UA was going to give me anything. I just walked to the hotel of my choice, bought some pajamas, contact lens solution and a tooth brush and went to sleep. The carrier, who of course isn't Chase, was fine. It's not like they don't do this stuff day-in-day-out. The portal was relatively easy, and UA issued a delay letter in about 2 weeks. I got the maximum amount they'd pay for the hotel, and paid the difference out of pocket. Much easier than waiting in line for a voucher, then getting in line for the shuttle to HoJos. That said, my last mechanical misconnect, I took the UA hotel voucher, at DIA, and it was fine as well.