Please correct me if I'm wrong:
Vk1 lasted 2245 Sols
Vk2 lasted 1281 Sols
Sojourner lasted 92 Sols (?)
Phoenix lasted 151 Sols (?)
Wikipedia knows all. But ...
VL1 was successfully commanded (to do the wrong thing) on sol 2252. It landed on sol 0, so that's 2253 sols of operations. The place that messed up the sols also messed up the Earth date (11/19, 1982, not 11/13). VL2 lasted 1316.1 days, or 1280.9 sols, so I'd buy 1281 (even though it was probably 1 more, with the 0.9 divided between partial first and last sols). [JPL Pub 82-107]
Pathfinder was under ground command for 83 sols (1-83), and experienced the undervoltage trying to wake up for sol 84. Some level of communication followed, but ground command was not reasserted and the science mission had ended.
Umm, Sojourner lasted 83 sols, too, and was lost when its communications subsystem (ie, MPF) failed. Speculation about what happened on/after sol 92 is just speculation.
Phoenix successfully finished sols 0 through 151 inclusive: 152 sols. (Again, signals without command authority followed.)
So, 3769 combined sols without Sojourner, 3852 with. So with 2 MERs, I get 2009 June 14 around 1900 UTC for a DTE or nominal beep from Opportunity or about 5 hours later for a UHF pass (to exceed all other landers/rovers). Actually, I get May 3 without Sojourner, with other errors canceling.