If you do not get concessions on the internal flights then as Valencia only seems to be about 70 miles from Caracas I'd suggest flying to CCS and then getting a bus/coach to Valencia ... see <a href="http://www.aeroexpresos.com.ve/" target="_blank">http://www.aeroexpresos.com.ve/</A> for times and fares.
I think that for Margarita you may have to bite the bullet and pay for commericial ticket else it appears to be a 5hr bus ride..