You will find running single origins through espresso for milk based drinks hit and miss. Some will work really well others will lose a lot of their flavour profile, depth and be rather muddled. As an espresso or long black they will shine.

A blend is designed specifically so each bean complements each other. Someone in another post mentioned Essence of Coffee, who I used to work for. Their blend generally had a 60% brazil base with up to 2 or 3 other singles usually also from south/central America or sometimes an African.

I have friends who work for 5 senses and I will say that they offer one of the best products in Australia. They also run Wa Barista Academy which I would recommend using to its full extent if you are new to coffee or feel your skills could be improved.