Reduced risk of STDs and unplanned pregnancies is the most pragmatic one that comes to mind. Also, better communication, for people who are into that kind of thing (i.e. most women).
Well, that's a different question. The advantages of lesbianism for any woman who does have that capacity are so many that I'm surprised more women don't adopt this way of life. [The obvious disadvantages are discrimination, no way to get legally married, and much harder to get pregnant.]
The HUGE advantage is that you never need to worry about unwanted pregnancy, birth control, abortion, etc. These just don't exist in your world. I think any single heterosexual woman can appreciate that.
There is a lower risk of STDs and domestic violence.
And of course, there is a tremendous sexual advantage. The person you are making love with has the advantage of knowing how your body works, what you're more willing to like, and is more likely to be compatible with you in terms of pacing and approach.
Also a more subtle advantage in individual expression. It's O.K. to be and express anything from lipstick and stilletos to cowboy boots and jeans. There's a tremendous freedom in expressing your own individuality without concerning yourself with what might be attractive to men. That's the big thing for me. Certainly you enter a world where you never need to worry that your accomplishments or assertiveness threaten your mate. Quite the contrary.
And small advantages: comfortable shoes, more and better dancing, ability to borrow mate's clothes...
I highly recommend it to any woman who has the capacity. And you may have it and not know it unless you try it!