I find scales enjoyable to practice (albeit when they're new and somewhat difficult...). Lately I've been practicing major and melodic minor scales (one day I'll do all my major scales, the next melodic minor), but I've been using different fingering, mainly 1 - 2, 1 - 3, 1 - 4. What I mean by that is 1 - 2 would be playing the scale using only your first and second fingers, alternating. I go 2 octaves, right hand only, left hand only, then hands together. I do this for those three variations (thus I end up playing the same scale a total of 9 times, left hand, right hand, and hands together for each of the 3 fingerings).
1 - 4 is the hardest, but after doing this for a few weeks now it's not nearly as awkward anymore. I play them with the metronome at 46 (half note)... when I started this metronome was at 60 (quarter note) or just not used. I feel it's important to stress this point... if you try and practice this fast right away (especially 1 - 4), you WILL hurt yourself, GUARANTEED. I'm finding it really fun though, and what's more is after I'm done I'm REALLY warmed up.
Oh something else I've been working on off and on for the past few months are some Chopin Etudes... Etude 12 opus 25 is a good one.