I will be in Estonia to attend a conference in May. Right now I intend to fly into Copenhagen for three days, visit Stockholm for four days, ferry to Helsinki for three days, travel to St Petersburg for two days, and on to Estonia for 10 days then home. What do you think will be my most economical way to fly back to San Francisco? Should I book a flight out of Copenhagen (round trip)? What do you recommend?
Nobody can really answer this for you. There's little about air fares that is rational to humans. You just gotta check all your options and figure out what works best in your specific case. Takes some investment of your time if you want to optimize things. There are no secret shortcuts or magic formulas.
I am not sure what your exact days are in May, but, you might want to take a look at Norwegian Air. You can book one way flights with them for a low rate. Many airlines it is more economical to book round trip and not open jaw.
.*..... more economical to book round trip and not open jaw.......* That is just not our experience. Most of our trips are open jaw and rarely are they more expensive than a RT and especially if you factor in time and money to get back to your starting point. We have even found open jaw tickets to be cheaper. But you do need a decent airport to fly from. You might need to take a short flight from Estonia to a bigger airport for the return. Unfortunately you need to get on a good airline search engine and plug in different options until you find one that is acceptable. The is no single, magic answer except --- do some homework.
Also, I believe you need a Russian issued visa to visit St. Petersburg. That can be expensive and pain to get.
As mentioned, predicting air fares is like predicting lottery numbers. But it sounds to me like an open jaw ticket to Copenhagen and home from Tallinn would be the best. A return ticket to and from Copenhagen might be cheaper, but then you have to add the time and cost of going back to Copenhagen from Tallinn.
Regarding airlines I'd suggest you look at SAS as they have direct flights from San Francisco to Copenhagen and will sell you a ticket home from Tallinn if that is what you prefer. They currently have a winter sale, but it might only be for European customers (you never know with airlines).
Thanks everyone. I went to kayak and google flights. I am still figuring out my multi-city flights.
You may want to check prices on SAS. They have some really great prices right now, including open jaw with non-stop from SFO to Copenhagen and 1 or 2 stops returning from Tallinn. I found routings with base flight prices under $700 for approximately 3 weeks on random dates in May.
I use the webjet site to compare flights (webjet.com.au) - it seems to have better coverage than Google. I then always book direct with the airline. On the St Petersburg visit - if you go by ferry from Helsinki (and then return to Helsinki by ferry) you don't need a visa for less than 72 hour stay. This lets you satisfy the 'must be on a tour' requirement. There are lots of mini cruises to Helsinki - Tallink Silja and Viking ferries both offer them.