Great work! I especially like first and second ones. On the ballet dancers (last one), maybe it would help giving some lighter values to the sky outside the window, to make the background look less dull.
And keep posting! that's a very nice start.
thank you guys for your comments. Yes, I agree, the one with the two dancers is somewhat dull, was my first try with two figures which did not really exist. There was one model alternating poses, but the space around is completely made-up, have never tried it until then, so hopefully will get better.