Tours typically last anything from a week to 12 days, although if you're looking to combine your trip with a few cultural stops around the Iberian Peninsula like Lisbon, or perhaps head onto Morocco afterwards, month-long itineraries are available.
Though temperatures are balmy year-round, the best time to cruise to the Canary Islands is generally outside of the July-September rush, or off-peak January to February. This said, it's worth looking out for last-minute summer deals online, as you may be able to get a full package for a fraction of the price, often with things like meals and drinks included.
Nearly all major cruise lines travel to the Canaries every year, so it should be fairly straightforward to find an itinerary to suit you. Another advantage of cruising Iberia and the Canary Islands is that you won't need to exchange your Euros every time you dock and with reliably warm weather throughout, there's no need to pack for different climates. Simply kick off your deck shoes and prepare to be escorted around some of the most enviable holiday destinations in Europe, all in the space of one trip.
Guided excursions on-shore are normally extra, but with historic cities like Santa Cruz de Tenerife, exploring independently is often just as appealing on a cruise stop here. Remember to check out the old town of Vegueta if your ship is calling at Las Palmas, and don't miss a day trip around the mountainous landscape of Timanfaya National Park on Lanzarote.