First of all don't do only 1 movement. That's lame
List of beginner piano concertos:Johann Christian Bach: Op.13 No.4 & No.2
W.A. Mozart - Piano Concertos K. 107 based on sonatas by J.C. Bach
Anton Stamitz - Piano Concerto in A
Tommaso Giordani - Pianoconcerto in C
Carl Ditters Vond Dittersdorf - Piano Concerto in A
Joseph Haydn - Piano Concerto in D, Piano Concerto in G
Dmitri Kabalevsky - Piano Concerto No.3
Nicola Lentz - Piano Concerto No.1
Feliks Rybicki - Piano Concerto for small hands Op.53
Next step would beW.A. Mozart - Piano Concerto No.12, No.23, No.26, No.19, No.22
Ludwig van Beethoven - Piano Concerto No.1, No.2
Isaac Albéniz - Rapsodia Española Op.70
Dmitri Sjostakowitsj - Piano Concerto No.2
If you want to do a great romantic piano concerto and you like a bit of a challenge. Choose
Rimsky-Korsakov's Piano Concerto in C# minor Op. 30 It's very impressive, not too difficult (easier than the Grieg) and it's about 15 minutes (3 shorts movements, no pause)