Wanted: Theme Suggestions

I need a WP theme easy for a client to update on a regular basis. I already created the website, but it has not proved easy for the client to manage and I was not happy with the features in the end.

They want widgets so all they have to do is insert text and images on the homepage. The layout has a header with a logo on the left and social/search icons on the left. Below that is the main menu and below that is an image slider almost the width of the page. Below the slider I setup three columns so the client can insert images with a heading(h1) above it and text below the image. This is where three widgets would come in handy so the client cannot mess up the layout of the columns by adding different sized images and using the wrong header size.

Another important feature of the website is a page that lists art classes. I set this up so there is a title/description, image, and a register button. I gave them a written template on how to replace text, images, and links as their classes change, but they were not able to follow it so I am looking for an easier option. They use eTapestry for their database management so I basically link a register button I created in the CSS file to the website page where they add items to their cart.

This website initially started as my internship, but I am also a member of the organization. I offered to do the updates for free, but they insist on doing it themselves. I want to give them a website they are really happy with and one they can update easily. They have 3 different people updating it so it has been difficult to train each one.

Is it possible to customize a WP theme and still make it easy for the client to update? Any theme suggestions or advice?