I first started roleplaying on an MMO, LOTRO to be specific. There is a lot of tavern RP to be sure but there are handfuls of people that do events and will RP battles or a mission of their own creation. It's a lot faster pace of course and space is limited for exposition. On the positive note, you have your characters there and can actually perform what is being written (to a certain extent). I had some great times with a core group of people playing as Rangers and later Rohirrim and we came up with decent story lines rather than play through the game's quests. As for long posts, if I could find a mode that removed the restriction for character limits that would be great, otherwise we just use '...' and continue on. Trust me, there are a lot of wall of text posters and the main hub gets a little crowded with it sometimes. I prefer to take my RP out into the world myself. Or you can form a group and have a private chat room in game and not worry about flooding other people's chat logs or offending anyone. 

The visuals added a nice touch to the story telling. I might be biased as I cut my teeth on it but it was a lot of fun and I still occassionally RP in that game though my regular group is all but gone. Most MMOs have certain servers that are dedicated to RP, whether officially or just communities have grown there. LOTRO has a lot of RPers and their cosmetic system is great, they also have a place for a bio on the character sheet which as far as I know allows for an extensive CS. It's F2P and if you like Tolkien that's a good place to start. I suggest the servers Landroval if you're in the US or Laurelin if you're in Europe.

I went from RPing in game to Advanced, and I still enjoy both. Finding the people to do it with is the tough part, but read the forums of whatever game you choose, see if people are posting events or advertising kinships/guilds that are geared towards RP. Good luck!