Less vulgar alternative to "bee up my butt"

Solution 1:

If you want to convey a sense of a sudden desire to take drastic action in a graphic way without any impropriety you might say, "He got a burr under his saddle." If a horse you are riding accidently gets a burr under the saddle he will start bucking, twitching, and snorting for no apparent reason. This was a common expression in western movies in the USA. I've never been on a horse, myself. If you want to be vulgar just change it to "He got a burr up his ass."

Solution 2:

To have a bee in one's bonnet (Dictionary.com) can have a similar meaning.

Solution 3:

To up and take off for an exotic vacation is an example of "get(ting) a wild hair".

The Online Slang Dictionary explains the likely origin and definition of this expression:

get a wild hair

noun - The correct spelling is "wild hair." A wild hair is a phenomenon found around horses. A hair from the horse's tail may fall into the water trough. Sometimes fungus or mold on the hair will make the hair wriggle through the water as if it were alive. Last edited on May 08 2015. Submitted by Anonymous on May 08 2015.

verb - to get a wild impulse. I couldn't sleep, I got a wild hair.

Solution 4:

Trying to keep with the theme of insects, I would recommend the construction bitten by the ______ bug

Develop a passionate interest in a specified activity:

Joe was bitten by the showbiz bug at the age of four

And specifically to your second example:

bit by the travel bug

Solution 5:

Well, I dont know about the ‘obsessive need’ part, but when you're talking about a ‘sudden or capricious idea; a fancy’, a great word to use is whim.

Alice: So what made you want to plant a garden in your front yard?

Bob: Whim.

Dave: Where has Eve been all week?

Char: On a whim, she and her husband flew off for a tropical vacation.