Aruba would be an amazing honeymoon! The resorts tend to be a little less expensive in the summer as compared to the winter with some of the resorts having specials like stay for 4 days and get the 5th free. You need to investigate fully.
I just realized Air Canada does not fly to Aruba in the summer. Check US Air, United, Continental, American Airlines, and Delta. Not sure if Jet Blue is an option for you as it does tend to fly out of the Eastern US, which doesn't make much sense to go that way from Vancouver.
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Rui, we had a number of friends stay there and they didn't love the food and found the whole "reservation" process for dinner frustrating.
As far as I am aware, this is not a "Riu thing". We have stayed all incluisve in Jamaica and Aruba and no matter which AI, you were always required to make reservations for ala carte restaurants. At Divi/Tamarijn you can take your chances and see if there is anything available late afternoon but the restaurants do not take "walk ins".
I wouldn't suggest doing all inclusive in Aruba, despite (or perhaps because of) the fact that we've done it a number of times. The only reason we did it the last time was so we were close to where my in-laws were staying.
The only benefits for us were that we love the beach at the divi and we tend to spend more time relaxing when we have a room right on the beach.
As for the price of the flight, you can save $400-$500 on the flight by leaving from Seattle. Depending on where you live in the Vancouver area, that may or may not be an option for you.
What my friends told me about the Rui dinner reservations was that you had to line up at 8:30am to get your dinner reservations for the non buffet restaurants for that day. People started lining up early. Also, you had only two options for dinner times. One was early and one was late. They commented that the space at the restaurants were small vs. the number of rooms and people at the resort.
AI does have its benefits but personally, we enjoy the timeshare experience of having our own kitchen. We tend not to overeat and drink during the day and save our best meal for going out for dinner. We buy soft drinks, bottles of water, alcohol and a Styrofoam cooler all at the grocery store and bring down what we need to the beach.