The pork shoulder has some heavier/stronger flavors, so, as mentioned, will do fine with most any smoke wood.
I have recently been using a trio of primarily cherry (stronger fruity aroma/flavor), pecan (mildly pungent aroma and slightly nutty flavor) along with a shorter period with hickory (sharp flavor and aroma). This has been my favorite combination for butts thus far.
Choice of smoke woods will inevitably become a personal preference after you play with some different species, so my advice would be use what ever you have on hand or can easily acquire, and as you change some of the variables, you'll find what overall flavor/aroma profile you like best. -t makes for more interesting dining when you change things up now and then.
Have yourself an enjoyable and smoky weekend!
Eric