I try to get to the library every week or so, and I try to get to a second branch that is just a bit farther away, but has a different selection than the one closest to me. Something i have found in my local library system is that you can't just walk in and hope to stumble into the place with the comics. Some amount of effort is required to truly make the most of your experience. I can't think of another interest that really requires you to work as much as comics do, in order to see the full extent of the libraries collection.
Here are some reasons for that:
1. Comics are a medium, and not a genre unto themselves.
2. Lots of different VOLUNTEERS shelve books in a library
3. Many folks don't realize item 1. in my list.
4. 741.5 exists in three different places in the library(as most classifications do). People often assume the target age of specific comics incorrectly
5. Lots of good comics that would be of interest to readers of all ages may be in the children's section, or young adult section, or the 'adult' non-fiction section, or all three (see #2 in this list)
When I go into the library now I look in probably 6 different places. They are as follows:
1. Two sides of a column next to the children's section. This is where Card Captor Sakura is, as well as a lot of Marvel Age single issues in hardcover, Baby Mouse, Owly, Asterix and Some Tin Tin.
2. Spinner racks not far away, between the young reader section and the children's non-fiction. The bulk of the manga is here. Fruits Basket, Sgt Frog, Prince of Tennis, Ranma 1/2, etc.
3. A separate 'end cap' shelf unit near the spinner racks, but closer to the Young Adult section. This is where the 4 or five Minx titles I have checked out were shelved, Age of Bronze, ElfQuest, Chiggers, Castle Waiting, Invincible, and a ton of other good stuff that ranges from children to Adult, but is mostly appropriate for a YA section.
4. The Young Adult section itself. More items are shelved here. It isn't all overflow, I think some people just didn't get the memo. If you don't check here, you may miss titles, or volumes from titles found elsewhere.
5. 'Adult' Non-fiction 741.5. This is where The Buddha Manga series was, as well as I shall destroy all civilised planets, Shadow of No Towers, Marvels, Planet Hulk, Heroes, as well as collections of comic strips from throughout the ages, and most books about the industry, or the medium and the art. Eisner is here, McCloud, Ten Cent Plague, etc.
6. Maybe it was just 5, but I strongly recommend doing a full recon mission on all the sections and displays in your local library.
If you aren't already familiar with all the libraries within twenty minutes or so of where you live, you should be. There is a vast amount of stuff out there. No-one is hurt by being well read. If you can't find something in your library, you should look it up and consider asking a Librarian about doing an interlibrary loan for it. Even if it isn't in your system, they may have privileges with local universities, or other systems outside of your immediate area. Libraries are buying graphic novels and books on comics, the industry, and creating comics. Let them know how much you appreciate their awesomeness by borrowing this stuff from them (and returning it on time... be responsible, people).