I'm about to spend a week in London, and I was hoping to get some advice on transportation. Does anyone know if it would be better to go with an oyster card or a 3 day travelcard in terms of more economical? And advice would be appreciated.

If you'll be there a week, then the 7-day travelcard would seem to be the best bet... can't imagine why you'd only get a 3-day. Are you wondering whether it's cheaper to buy two 3-day travelcards?

It's just I didn't see a 7 day card as an option when I was looking at the website. Is there a 7 day pass? If so, how much does it cost?

I think you can put a travel card on an oyster if I am not mistaken

My apologies; 7-day travelcards are discussed ad nauseum on this forum, but I see now that it's not very clear they're an option if you're not familiar with the TFL web site (tfl.gov.uk). If you look under "Tickets", then "Get Oyster Card", scroll down to the Travelcard section. 7-day travelcards are the first option in the dropdown.

Honestly, the simplest and best thing is to wait till you get there and ask the ticket agent for help. In my experience they've been quite helpful. My guess is that you'll wind up getting an Oyster and loading it with a 7-day travelcard (you'll most likely only need one for zones 1-2). The only complication there is if you want to use any of the 2-for-1 deals, which may require a paper travelcard; I've not done any of those, so if that's an interest for you, you'll want to do some searching on here, or ask someone who knows.

I agree. You're best best is to get there and ask someone in the Tube ticket booth. I was there for five days, but I was informed that it was cheaper to buy the 7 day travel card. My travel card was loaded onto an Oyster Card. I got a Zone 1-2 card, and the extemely nice gentleman said my best bet was to load the exact amount extra needed to go to/from Heathrow. Luckily, my hotel was right on the Piccadilly line, and there was no need to change Tube stations. This is what these people do, leave it to the professionals. I had a great experience and know that you will too.