I always take my electric shaver (bought in the USA) to Spain and only add-on the adapter prong-plug to the end and it works great.
As for laptops, while I've never tested it myself, I understand from many many people that laptops are rather universally useable, all having a built-in power converter into the cable - the rectangular box towards the end of the power cable. And there too you should be able to use the simple plug adapter stuck onto your existing plug.
Madrid
Man is correct.
My electric shaver, laptop and digital camera's battery recharger are universally and only need a adapter to plug it in the outlet.
To be sure that your devices are universal, can use used in US and Europe, check the power supply of the device. You should see somewhere printed 120/220 volts. This indicates you can use it in US and Europe.
Also you should be able to find this information in the owners manual, usually in the back were they list out the spec of the electric device.
On my electric shaver is say 120volts/220volts where I connect the power cord.
I only bring one adapter on my trips and extension cord that is eight feet long. Many outlets in hotels/B&B are usually not located in a conveniently to plug an laptop into. Also if it late I will usually backup my photos to my laptop while I am in bed. So I plug the extension cord in the wall and plug the laptop and camera's battery recharger into that.
Bill