What is a good port wine?
I like wine and champagne that have a sweet taste to it, I am not a huge fan of alcohol/fermented drinks, but I do occasionally like have a glass of wine or champagne every now and then.
What is a good quality white port wine and champagne to enjoy?
Well, besides the fact that "best" is a relative term, and highly individualistic . . .
My favorite White Porto is from Churchill's -- http://www.churchills-port.com/ss/wine/port-list/dry-white-aperitif/ -- which is, in fact, a 10-Year Old. Second is Niepoort -- http://www.niepoort-vinhos.com/en/ports/ (scroll down) -- which, by the way, produces THREE different White Ports (traditionally sweet, dry, and -- like the above-mentioned Churchill's -- a 10-year old). Third is Barros "Very Old Dry White" -- http://www.porto-barros.pt/
As far as Champagne is concerned, there are literally dozens and dozens of GREAT Champagnes out there -- perhaps if you gave us a price range, it would be easier to make some specific suggestions.
As an alternative to white port you could look for Pineau de Charentes - it's a French fortified wine (i.e. cognac has been added) - comes in red and white varieties - the white should be served chilled. It is available in the USA (but not everywhere) and is quite pleasant. White ports are generally pretty cheap and not particularly highly rated but quite pleasant to drink. Until your alcohol tastes mature you don't need to pay much and certainly don't need to delve into vintage (red) ports - but some of those are sublime - I polished off my last bottler of Graham 1955 vintage port about a decade ago - it was unforgettable.
Here is brief a primer on port:
Real port is made in the Douro valley of Portugal and comes in a variety of styles. It is a fortified wine (has alcohol added) so it runs 19-20% typically. There are versions that can be ok from Australia, California, etc., but the real stuff can be had for a reasonable price, so give it a try.
A port house generally has a range that goes something like this: Tawny, Ruby, LBV, 10, 20, 40, etc. year old Tawnies, Colheitas, Vintage. If you aren't familiar with port, try a basic Tawny or Ruby from a good house. A Tawny will be slightly 'browner' from being made in a way that oxidizes it slightly and one gets nutty/raisinish notes; a Ruby will be 'redder' and less oxidized, stressing the fruit more. You should be able to find basic ports like these for $10-$20 bottle, depending on where you live.
The LBV (late bottled vintage)is a more deluxe version of a Ruby, from a single year, which sees aging at the winery, where a Vintage is normally the best of the non-oxidized style from a single vintage, which, to be at its best, is usually drunk 20 or so years after the vintage. American wine geeks like to talk about these wines. The dated Tawnies are aged and blended in the winery to mellow them and increase the complexity, while Coheitas are similar, but are single vintage wines. If you like the basic Tawny, then these might be worth exploring.
No specific brand recommendations, but most of the big port houses make some good products and have certain house styles. Depends a lot on what you have in your market. I'm leaving out a lot (e.g. white port), but try the basic stuff and you can get a idea. One nice thing about most port is you can keep it around after opening for several weeks and it will still be drinkable.
Oh, I missed the fact that you were specifically asking about white port. Unless you live in a major market or an area with a Portuguese community, you will probably not have much selection in white. There are dry and sweet styles, and the Portuguese often use them as the base for spritzer-like drinks on ice in the summer. For the really sweet style, look for those labeled "Lagrima". There are some more serious white ports too, often with a year designation (like an aged tawny) or colheita types. A few years ago in Porto I had a glass of 1952 Dalva colheita which was very interesting, but this type of wine is expensive and rare.
Don't know any white ports, but I do like Meyer Family Port.
I would also suggest trying Prosecco (Italian Sparkling). It does not have the savory, yeasty notes of champagne. Has beautiful primary fruit/floral notes. If you want something even sweeter, try Asti (Italian Sparkling).