No one uses a website because it's pretty. Everyone uses a website because it's useful. It's a testament to human superficiality that in 2013, there is still such a thing as a 'web designer' for sites smaller than 20,000 uniques a month, while many of these same sites (and many much larger sites!) are usability nightmares.
Hiring a designer when you don't have a UX consultant is like sending interior designers to Louisiana after Katrina: nice, but it would be even nicer to get the levees rebuilt, hmm?
(Sorry, I'm on a bit of a rant; I hope it is informative enough to justify its irate voice. Allow me to continue just a bit longer.)
Do you have a tailor make your jeans? No. Do you have a haberdasher dash your hats? No. Do you have a cobbler hand-cobble your shoes? .... So why are you paying someone to put e-lipstick on what might very well be a www-pig?
So, go to useit.com and read up about usability, and then hire a UX (user experience, or usability) expert. Go get yourself a website that works as good as it looks. Because you deserve it --- and so do your visitors.
I like to use the template method. Give the designer 2 - 3 generic wire-frames that mirror your site's major "views" or function. Also request a generic template for 'leaf' or low level pages to use in the future for new content pages. Deliverables should be valid PNG/HTML/CSS/js files. Next map these new templates to the various pages in your site, and put the content and navigation together. This is old school webmaster work and any staff person with HTML skills should be able to do it.
I prefer the above method to giving designers free reign. But the decision makers must do their part: commit to a design and not allow feature creep. It also ensures that you can maintain the site going forward yourself or with just an HTML hacker.
Contact a local university or use craigslist.
99designs is also good, but it's more generalist marketplace vs the two I mentioned