Any electricians available? Wire size question...

I'm wanting to run power to my shop, which is about 250 feet from my house. I don't need to pull a lot of amps, but I want a 240 circuit as well as lights and outlets throughout, the shop is 30x60. I'm thinking a 100 amp sub panel will be fine, and I won't have to worry about overloading my main panel.

I'd like to use "direct burial" aluminum service cable. There are many many different types of cable, some with a total of 3 conductors, some with four.. Sometimes the neutral is smaller than the main conductors. The one I'm considering is:
300' 4-4-4 Aluminum URD Vassar Triplex cable underground wire

Does this seem appropriate? Overkill? Too small?

Thanks!

Mark