mike dmt, a bit of silicon on the weatherstripping will help with doors freezing shut. Freezing open is probably latch not releasing due to the short piece of bowden cable for the door handle having a groove worn into it. If you take the oval access plug for the lock out and spray some lube in there it can help for the short term.
My list includes refurbishing the headlights, getting the headlight washers working, maybe replacing some PDC sensors, heated rear seats.

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1988 325is (purchased new) sold
2004 X5 3.0 2005 X3 2.5
2008 X5 3.0 (new to me)