Mike the Knight/Bob the Builder

I'm a big fan of using edible dusts to create depth in the recesses of the cake texture. Like between some of the bricks and the stone path, maybe cutting out some extra fondant bricks to put on top of the brick texture so the whole thing doesn't look so "flat" . I would have also spent a little more time on the windows, maybe carving out a niche and pressing the black into it, creating a border w/ a keystone at the top?
As you said about the grass...not a fan of using most kind of icing tips. I do the majority of decorative accents in fondant. More costly, but gives it an updated feel, tips always seem so old school to me...AND I SUCK at piping with tips so I avoid them at all cost..lol!
Board definitely smaller and piping gel tinted blue for the water. I can't tell what you did for the water, icing or gel?
But it looks like a solid cake....so great job!

Cake Club: Here's my tip on grass...I use about 3 different shades of green. It really makes a huge difference. I can tell you twisted to pipe in different directions that helps as well. I would also use a bit thicker frosting and/or pipe shorter bursts. The blades of grass won't fall over as much.
I really like the stones & boulders! I agree about using a bit of dust or marbled fondant or an air brush to get a little depth.
I don't think the board is too big. I think the dimensions of the cake make it feel a bit wide versus tall. maybe another turret on top or something would have added some balance.
By the way, so glad you laid the water before piping the grass! That's how it looks on the bank.

Cake club comment: I really like it. Your proportions are nice and the imprint on the fondant castle is very well done. Agree that variegated colors on the grass would look nice. Personally, I prefer piped grass to fondant. I know we all want to roll our fondant and gumpaste as this as possible but in the case of the battlements on top of the walls, I would say thicker would be better.

Cake Club: I like it. Woul probably use piping gel for the water, just for added depth. Personally I think a tree or someting in the background would have helped with the overall feel, adding depth and dimention to the background. Perhaps an arched bridge over the creek, the flat walkway is a bit off.
I really like the way you brought the two themes together, it totally works.

I agree on adding some dusts to the detail in the castle, and to some more height to the castle. Board a bit smaller, trees or bushes, and an arched walkway and thicker gumpaste. Cute way to bring the 2 themes together!