They are cool
mind if I give some tips?
Years since I used bryce, I moved onto Vue, which currently is much better app.
1) One of the most important things about an image is lighting.
Real lighting is rarely "hard", look at the edges of your shadows: very sharp, and that lends an unrealistic air to them.
Now, bryce CAN do soft shadows, but too many years since I've used it to remember the exact controls.

Any light, including the Sun should have a control to give it degrees or amount of softness.
Noon Sun maybe 1 or 2 degrees, 5 degrees usually, 10 degrees for candles etc.
That does boost the render time up a LOT, but makes it far more realistic.
Another thing is to use "Light gels", which break the light up, or volumetric light which looks really nice coming through windows/leaves (but has huge render times)
This is pic I did 8 years??? ago to show soft lighting in Bryce:
http://www.silverblades-suitcase.com/artofadreamer/3d_2/lich3_three.jpg
2) Real "ground" is never flat, easy way to make it look more realistic is to use a terrain and flatten it a lot, if the feet don't match the ground perfectly, I use rocks under their feet or grass nearby to either balance or hide things.
My tutorials, cover lot of stuff, and even when it's for Vue, some of the principles still apply to Bryce
My Tutorials Index