According to this survey by Hotels.com, Tom Hanks was named favorite male celeb to vacation with, while Jennifer Aniston was named favorite female.
There are definitely a lot of celebs I think would be awesome vacationing with, like Adele, but I think Tom and Jennifer would make the PERFECT all around vacation buddies.
The rest of the Top 5:
Male -
1. Tom Hanks
2. George Clooney
3. Denzel
4. Morgan Freeman
5. Justin Timberlake
Female -
1. Jennifer Aniston
2. J-Lo
3. Ellen
4. Selena Gomez
5. Beyonce
(source: Expedia)