For me, they did use some difficult words in Risou no Musuko, but it's not essential for the story line. So it's alright to practise with.
I watched Barairo no Seisen without subs and I don't think I missed out on anything. I thought it was pretty easy, but you do have to like the story to watch it. It's a special (6 eps) and it's about a young mother who becomes a model but has to balance her debut with taking care of her children. And her problems with for instance her husband who is against her having a job. So that means you have to like fashion a bit and it's also quite feministic. I liked it though.
Muscle Girl is also easy. It's about a group of girl wrestlers and a Korean idol undercover who gets mixed in their struggle to keep their wrestling organisation that's about to shut down. (Lee Hong Ki from F.T.Island)
Switch Girl is also very do-able, it's a typical romcom but it's taken from a manga so it's especially funny (you do have to like the humor though, it can also be a bit gross-awkward at times) and the romance moves a bit faster. It's about a really slovenly girl that puts on a stylish popular girl act at school.
But ofcourse practically every romcom will do, I hope I was of help to you! :)
(Also these maybe, though I'm not too sure: Zettai Kareshi, Yamada Taro Monogatari, Deka Wanko, Scrap Teacher, My Boss My Hero, Paradise Kiss, Lovely Complex, Mendol, Kingyo Club, Kimi wa Petto, Kimi ni Todoke, Hyoten 2006 (one of my favs!), High School Debut, Gachi Baka (Very alike to Gokusen), maybe Buzzer Beat and Anego.)