Tomorrow dh and I leave on our next adventure, a month-long trip that will take us to eight European countries. The first leg of the trip will be two days in Barcelona followed by a 12-day Mediterranean cruise to celebrate a friend's retirement. Then we are back in Barcelona for a few days before flying to Geneva to spend time with my cousin. After a few days in Geneva, we'll take a train to Basel to begin a one-week cruise on the Rhine. Our trip will end with three days in Amsterdam before returning to the USA.
While planning the trip I discovered it's sometimes cheaper to buy a round-trip ticket, even though you just need a one-way fare. For example, a one-way flight on Swiss Air from Barcelona to Geneva was $592 (Economy Class). By booking a round trip ticket, I paid $177 (and it is Business Class to Geneva and Economy Class for the "return" trip). Baggage weight limits are lower in Europe and we each have a 50 lb. bag. Business class allows more weight, otherwise I could have spent ~$35 per RT ticket.
Other savings: I booked the first cruise through Costco Travel, and even though the price was exactly the same as through Royal Caribbean, Costco gave us a $500 on-board credit. The river cruise was a 2-for-1 special on Viking. I will use my Chase Sapphire card to pay for hotels in Barcelona, as well as meals and extras, because there is no foreign transaction fee with this card. And at home, I saved ~$150 by putting the garbage, paper, and TV satellite on hold, and by skipping one of our bimonthly house-cleanings.