The problem with many longer length dresses is they're either summery maxis, or long-sleeved, covered up styles that run the risk of looking really frumpy. This dress is neither. The Pinup Girl Clothing Jessica dress is the ultimate va va voom cocktail dress, but the hem sits lower on the calf than most dresses of this style. The plus sized version (in black or red) goes up to a 4X but they sell out really fast so you may need to join a waiting list. That'll give you enough time to save up for the international shipping costs that'll be added on top of the $98 price...but maybe this is one dress that's worth it for a special occasion?
On the other end of the price scale comes this peacock print dress from Just Curvy (£27, sizes 16 - 26). The rise and fall hem (I just can't bring myself to say "mullet") delivers some extra modesty without being a full length maxi, and the dark print means it'll work into the colder weather with tights or leggings and one of the many sleeve solutions I featured a while ago, or it can be stashed away for summer holidays.
If you're looking for more of a day dress, this classic stretch mock wrap (£38.50 at That's My Style) comes in a longer length that hits a few inches below the knee (longer, if you're petite). Don't let the non-plus model put you off, it's actually available in the biggest range of sizes of any of the dresses featured this week: 12 to 40. If the red floral print is not for you, it also comes in black.