As for houses, I still think buying the largest road you can, and filling it full of greenhouses to start with is a good idea, prevents random hazards. Only people that really get lucky can have a bulldoze then a hazard.
A street I had earmarked, has gone up to 1.5mill as a purchase price...but the rent from properties is more than the cost to build them!
Edit:
Also, on my first street (will aim for 1 per day till tax cap) I have found that:
10 x Greenhouse = 500k
Rent= 770k
1 x Grid Building = 500k
Rent= 69kk
I haven't yet checked the road rent increase on differing building types, as I haven't tried a 2nd account yet.