That advisor has shown me which planet to colonize. Only problem is it wanted me to colonize it with colonyship X that was three sectors away when CS Y was in the next hex to that planet.

Advisors are best ignored as they are only marginally useful, good only if you are a complete newbee  to the GalCiv franchise and then only to remind you that you need to Colonize, build a Fleet, could use this or that resource, ad nauseum.  

Minimize the core and colonized planet click one of the little icons above ( the tiny green, blue, orange) one of them IIRC the orange manufacturing one will put them in size order this will give you a good idea the "best" planet to settle.

You can also sort your ships by name scroll to the colony ships you have choose one and then mouse over the uncolonized planets in that sector. 

I too wish they had the choice to sort by size in the planet screen, but if wishes were wings Frogs wouldn't bump their fourth point of contact when they jumped.