WorldCon may be a bit bigger than Norwescon, but not all that much; typical attendance is 2,500-5,000. Plus, it'll be more spread out, so it may even feel smaller. Also, you'll have local friends there; knowing folks in advance always helps, as you can focus on finding/meeting them. If you scout out the terrain in advance, you can plan all the good places to meet up [especially for vittles].