Why not take a look at some of the ABRSM books, they cover grades 1 to 8, they do have some classical pieces in but they are easy depending on what grade book you get, and they have popular tunes in them as well. By the way I practice dominant 7ths for pinky exercise.
Im guessing youve already browsed melbay.com ? theres a bunch of stuff there. hal leonard maybe. also, check into books aimed at mandolin too. just make sure the transcriptions arent tab only. most include the "dots" with tab below the staff lines but the music will work for violin.
. I dont have anything specific to suggest in show tunes. The Portland books are well written and most tunes are doable and span a bunch of styles but most would probably classify them as fiddle tunes. Ive at random just picked a tune from them i didnt know and diacovered some cool stuff. Most are typical 16 bar AABB type stuff..iriah, New England, some old time, scottish, qubecois, canadian... lots to explore. all 1st position type tunes. One of the links we posted recently on the forum had a section with 60's stuff so look back through some of those. i cant remember which one had it though.