So, a good suit does not just come off the rack and fit you like it was made for you without any alterations. The only people who can get away with this are Models, and I'm talking proper runway models that do the catwalks in Milan etc.
90 percent of guys that need a suit, will have some sort of adjustment, wether its the sleeve or trouser length, the tapering of the back panel, or to let in or take out the waistband, most guys will need some sort of alteration.
But while your out shopping with your girl ( and I'm sorry as much as you love your girlfriend/wife or significant other. don't take them shopping for a suit.. they don't wear a suit.. just like you don't wear a bra, but do you give them advice about their bra fittings!.. really.. its one thing to say your tits look hot.. but its another to see if they actually fit her properly) ANYWAY BACK ON TRACK… When your out shopping for that new suit.. what do you need to look for when trying on a suit? Well there are many things, but the one thing I'll focus on here, is the sleeve length… YES the sleeve length matters ALOT.!
What do you think about this guys sleeve length… if you said its fine, you get a smack on the back of the head. and if you said its too long.. you step forward to the head of the class. This guys suit is was to long in the sleeve. Having a sleeve length too long says two things. 1. you didn't give 2 shits about making fit and 2. it makes the suit look like your wearing a size to big.
A suit sleeve length can vary.. but the main rule of thumb is to show just a peek of the shirt cuff coming out of the bottom of the sleeve. Any good tailor can alter a sleeve length from as little as $35.00 dollars! the Below image is a good example of where your sleeve length should be