<p>Paul,<br>
you could take a look at Smugmug. I never used Smugmug myself though I like their interface even more than 500px. As usually, there may be some pitfalls, depending on the nature of your photos: the site is known (and sometimes criticized) because of their 'family safe' policy. If you do not like such restrictions on content, Zenfolio is probably the best for you.</p>