Next step up after olympic triathlon?
 

What is the next step up in difficulty? So clearly there is the Ironman 70.3 and the full Ironman. But Ironman is just a brand name. I understand there are other companies that offer ultra-distance triathlons too, right? I ask because there are no Ironmans in my area and I want to see if there are some other forums of ultra distance triathlons I could participate in.

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Wikipedia
 

Wikipedia has a very good article on Triathlons. It lists all the different length with great detail.

The "iron distance" is spreading for non-IM-brand races. They have to be careful not to infringe on Ironman's copyright/trademark rights, but you will see races using the same 70.3 and 140 format. As @OldTryGuy suggests, do some googling and you might find some options near you.

Some other popular series with the same distances of Ironman and Ironman 70.3 are REV3 and Challenge USA triathlons. These triathlons are also very location dependent and hard to say if they'd be in your area or not. There are also many local races that do Half-Iron and Full-Iron races that aren't technically a series of races around the country. For these races you just have to do research and find a race near your location. I'd suggest Internet research and talking to some of your local triathletes who would be most informed on the races in the area.

Besides Google, hit up your local triathlon club (if you have one) to find out where people race. As Trekathlete mentioned, there are other series and stand alone races that cover a wide variety of distances.

My wife is planning a fall half through the HITS Triathlon Series as she makes the transition from olympic to the half. The Ironman series entry fees are too high for us to stomach.

People do travel all over for these things, too, they don't have to be local. I suspect that's part of the attraction to them, actually.