Angels and Discus don't mix well for various reasons and I personally wouldn't put Discus in a 33g. The prefer larger groups rather than pairs, high temps (86F+) and they need very good water quality (the smaller the tank the faster things can go wrong).
Also, the plec idea..........stay with small ones - clowns, tigers, butterflys, etc. Stay away from 'Common' plecs as these get upwards of 12" and will not only outgrow your tank but put huge strain on your filtration system.
If I was you I would wait a while, formulate a plan of what you want in the tank then research the fish and there requirements & compatibilty. You will find that the fish you have will grow bigger than you think and as parker313 says, don't overstock now just because the tank looks empty.
HTH