IMOH, the gloss paint is much easier to clean, but it seems to depend on brand whether it is tougher. Most of the time, the adhesion is better with a gloss. I would have to say the ease of cleaning can definitely add life to your paint job.

What do you mean?- a nicer look? If it is the brush marks in the paint sometimes a third coat won't help. You will have to try a better quality brush. I learned the hard way that a good quality brush will even make a cheaper paint look better.

It is fairly normal that a primer plus two coats of finish doesn't fully cover the stained wood when you are using white. White covers poorly and will cover especially poor when you are using a a bright white because there is less black in it. There is no disadvantage to applying more coats...usually, each coat will look better until you reach that point of maximum saturation and full color coverage at which point additional coats will do nothing. With modern day paints, I really don't think that you are going to get more durability from a gloss than you will get from a semi-gloss...not so much that will actually notice anyway. Some companies even make matte finishes that are pretty darn durable these days.

Peanutmom, I used a quality brush (it's just that I'm a perfectionist). I decided to apply a 3rd top coat in some areas & it improved the look. I think my problem was that I tend to put on too thin of a coat each time. Also, I did use a bright white which would explain a little less coverage. I purchased Floetrol to help eliminate brush strokes, but decided not to use it since the paint flowed on well. Also, I read somewhere Floetrol can yellow white paint a little bit?

BTW, both of you mentioned that some brands are tougher. Do you have a preference of brands & why?