A good "rule of thumb" is to aim for 2 cents per Hyatt point and thus value UR transfers with this in mind. For me, UR to Hyatt is an excellent value as I see a minimum 6% return on Sapphire Reserve spending.
I periodically do better than 2 cents with Hyatt but have to remind myself I'd never actually pay more than $600 for a room at the Park Hyatt New York so am I really truly getting more than 2 cents if the going rate there is $1,000 per night? Probably not.
Also keep in mind that using points eliminates paying Resort Fees - and if you achieve Hyatt status, still confers all the benefits of said status, including upgrades.... which again, for me arguably increase the value of Hyatt points well beyond 2 cents.