ok, my comment is not going to be on 'whats overplayed or not', but if these people havent heard Chopin Ballade No.1, then they probably havent heard much classical piano music or piano recitals. 2 Beethoven Sonatas will be too boring for the non-classical ear. you have to take yourself back to a time, maybe when you first got into classical music, or when you were less interested. At those times you prefer to hear more of the Romantics. ok you can argue about Beethoven being late classical, but argue from point your ear. they will get bored.
I totally agree, two Beethoven Sonatas will be too boring for the non-classical ear. And you should give them some Liszt as an Encore.
How about something like this?
1. Ballade No.1 Op. 23 -- Chopin
2. Piano Sonata No.14 in C sharp minor (Moonlight) -- Beethoven
3. Prelude Op. 3 No. 2 in C sharp minor -- Rachmaninoff
*Intermission*
4. Etude Op.10 No.1 -- Chopin
5. Any short and well known sonata (Less than 15 min)
6. Etude de Concert No.2 "Gnomenreigen" -- Liszt
Encore: Chopin's Heroic polonaise / Liszt's Hungarian Rhapsodies No.2 or 6 / Chopin's 2nd Scherzo.
That should make about an hour.
I'm not saying that you have to play exactly what I put on the program. They're just examples, and they must be well known. You also need to give them a virtuoso encore.
Good luck !

Alex