As with crochet, you can work a large piece in strips/panels/squares. So you don't have to have circulars for many patterns. If you've done a full afghan in crochet, you can get a sense of how heavy that would be hanging on circ ndls. Done in smaller pieces, and then joined, means a project that travels more easily.
You might want to consider doing dishcloth-type squares, perhaps in diff colors, and then joining them to make an afghan. Here's lots of ideas: