Booking UC for next Sept

After our recent UC experience to SFO and back from LAS we're well & truly hooked, so just looking at the most cost effective way of flying UC next year. We figured that as we have enough miles to upgrade from PE to UC a good option would be to pay for a PE ticket (of the right fare class of course
)and use miles to upgrade.
We love Dubai as well as West coast USA so are looking at both options. I was really surprised at the price differential between the two routes, i.e. PE return to DXB comes in at £806.50 whereas PE return to LAX is £1,278.40 Key question is, surely the PE figure quoted for DXB must be a fare class that doesn't allow miles upgrades. Would I need to call FC to find out as the web site doesn't state fare class?
Also interesting, to buy UC outright for DXB is only £1,206.50, whereas LAX is £2,872. So now I'm thinking there's no point using miles for DXB as we can get UC for around £1,200!
Any thoughts/guidance welcome.

We love Dubai as well as West coast USA so are looking at both options. I was really surprised at the price differential between the two routes, i.e. PE return to DXB comes in at £806.50 whereas PE return to LAX is £1,278.40 Key question is, surely the PE figure quoted for DXB must be a fare class that doesn't allow miles upgrades. Would I need to call FC to find out as the web site doesn't state fare class?
Also interesting, to buy UC outright for DXB is only £1,206.50, whereas LAX is £2,872. So now I'm thinking there's no point using miles for DXB as we can get UC for around £1,200!
Any thoughts/guidance welcome.