Hmm...just saw this thread. Just felt like giving my 2 cents but anyone can agree to disagree.

Looking for a professional interior designer is not a necessity especially if you have some budget in mind. Like some of the LYN members mentioned, referring to designer magazines, you can pick and choose the designs yourself, and find an experience (and specialised contractors) to do based on the designs. Experienced contractors/carpenters/KC suppliers etc, most likely will be able to produce almost 90% similar to the design you show, unless the contractors have own opinion that certain things can't be done (based on experience/your house structure's problem etc). Experienced contractors sometimes can provide nice and practical designs too.

However, if you have a little more budget and are a busy person, want things to be done without much time consumed by yourself as well as you want a very special (and no one else has) design, engaging a professional interior designer will suit you as they are supposed to manage through your entire renovation also.

So it's all depends on your needs, as well as whether you have deeper pockets.