postcards composition and colour development

I started collecting a range of photos of the scene I wanted to depict for each city so that I could start working out a composition.

I did some sketches of the scenes that I scanned in and worked from on illustrator:

I found that it took a lot longer than I expected. I had my image open on illustrator, which I was using as a guide to then use the pen tool to create the scene. But I hadn't thought about how difficult it would be to then colour in as I hadn't been making whole shapes with the pen tool so it was very frustrating. 
I also found it hard getting the perspective right, I tried using the perspective grid but I couldn't get it to align to the perspective I wanted. 

 I went back to working in my sketchbook, playing with composition.
I decided that what I was wanting to achieve was too complicated, I needed to simplify it down quite a lot - there is too much going on in each scene at the moment.

I thought that instead of focusing on detail, I should just use blocks of colour to represent the buildings and only have detail on certain areas - like the recognisable monuments.

Also started thinking about the colour scheme for the postcards. 
Went onto Adobe Kuler, where I could upload images and it picks out the main colours from the image, which I found really useful in deciding the tone I want for each postcard.