Just Do It
The maxi dress works on several levels if you choose the right one. The can be comfortable, flattering, and ridiculously easy with sandals (notice I did not say flip flops). They are ONLY for spring and summer.
The first is cotton jersey and looks as comfy as a night gown. I'd wear it to a daytime housewarming party or barbecue.
The second one looks really flattering and modern. I'd wear it to brunch or dinner.
The third is an example of how to do a wild, loud print. With a limited number of colors, the loud print reads as bold and fun instead of busy and overwhelming.
The fourth is one way to do the maxi dress in a semi-formal way. The color is a nice touch but it doesn't scream at you. And the halter is a little sexy.
However, there are many to avoid, which brings me to point number 2:
Run Far, Far Away
If you are really short, maxi dresses could work for you. A long, continuous line of color is elongating, but if the hems hits you above the ankle, like this one, it can cut off your leg line and make you appear stumpy.
Beware looking like mom. Some of these dresses come across as really dowdy, such as this little blue number. Flutter sleeves and a dated, conservative shape make this old and the maxi dress should be young and fun and happy.
Unless you are a bridemaid, don't do this to yourself. No, not even at a wedding/bar mitzvah/christening. Occasional exceptions can be made for mothers of the bride or groom, since they are to fit in with the wedding party to a certain extent.
Remember, darlings, evening gowns and maxi dresses are two different things, designed for two different purposes. The first is formal evening wear, the second more casual day wear.
The winter maxi dress is just awful. Trust me, it is not flattering. You can be a size 0 model and still look weird in this. First of all, it doesn't keep you any warmer than heavy tights and a much more flattering hemline. Second of all, it is really, really dated and dull. I would avoid it like the plague.
The shape of this dress is lovely, but all over patterns should be chosen carefully. This is a whole lot of springy/easter-ness. And it's too much. This print on a 4 year old seems much more appropriate.
If you avoid one kind of maxi dress, avoid the one masquerading as a prairie skirt. Don't let this dress fool you! It is not hip, it is not "bo-ho chic", it is not cute. It is just hideous.