How to spend a perfect day in Vienna when it's raining:

Meet a charming young lass/lad e.g. in the Café Kunsthalle on Karlsplatz for your morning dose of caffeine at any time convenient (they serve breakfast til 4 p.m.)

While you enjoy whatever it is you've ordered, listen to Shirley Bassey implore her lover "come on baby light my fire" and postpone all to do's until later

Make sure you brought your wellingtons! (I should have mentioned that first, sorry)

Do your shopping! (Nobody else will bother you today; the streets are all yours)

Show your prey to your companion-in-mischief over a coffeebreak

Pay a visit to an exhibit you always wanted to see but somehow never have found time to, e.g. Architekturzentrum in MQ

Have your dinner at I Ragazzi in Burggasse (if you thought of booking a table before, that is)

Watch a movie about Vienna in her past, e.g. The Third Man in Burgkino on Burgring (they show it every Thursday)

Have a cup of hot chocolate (with or without ron) for a night cap