<p>It seems that Silverlight/WPF are the long term future for user interface development with .NET. This is great because as I can see the advantage of reusing XAML skills on both the client and web development sides. But looking at WPF/XAML/Silverlight they seem very large technologies and so where is the best place to get start?</p>

<p>I would like to hear from anyone who has good knowledge of both and can recommend which is a better starting point and why.</p>

Silverlight is a stripped down version of WPF so it should have fewer things to learn inside. On the other hand, the two platforms have different targets (web & rich client) so I guess it depends on what app you're going to build.
If you just want to learn for yourself (no app in the close future) I'd pick Silverlight because it would be less to assimilate. Still, Silverlight is pretty much a moving target, much more than WPF, so you'll have to keep up with some changes from time to time (the joys of being an early adopter :)).
WPF has lots more stuff that you will probably want to use at some point but I would wait for the needs to arise first.