Having just stayed at the DT, I can't say I recommend it. If you want a Hilton property, stay at the Hilton at T4. Sheraton and Marriott all have properties nearby that are within the Heathrow Free Flow zone for local buses. The Renaissance (a Marriott Property) has some nice views of the airport. I'd say if you have any sort of hotel status, stay in that chain, otherwise the Hilton at T4.
Or Sofitel in T5, if someone else is paying.
