if the weather will cooperate, pick a park that none of your (hopefully few at age five) guests probably go to .. new play structures are always fun ;). Just about any park with a playground will do, although drive by first of course ... or on a weekend the school that your kid goes to or will go to (they can either show it off to their friends or explore what it will be like and gain some ownership into growing up) ... one park in my area has a cute 'bike race track' (actually a windy 2 foot wide pavement track) for preschoolers which we've had great success with, because kids can bring their bikes, trikes, scooters, skates, whatever ...
If the weather won't cooperate, there are likely some community rooms around (one here in Portland is only $60/3 hours!! and about 15ftx50ft ... perfect for family and a few small kids, with setup, 2 hr party, and cleanup time :) ) ... which is like "home" in that it is private, but not like home in that you don't have to clean it before you can decorate it ;)!
Also, no kid party should *ever* be more than 2 hours ;) ... it's not too much time to fill up ... on or two activities and cake+icecream, and you're done
activities: go to a thrift shop and see if there is anything that inspires you
yarn? spiderweb games, wrapping sticks to make magic wands, etc ... this summer we made pom poms and tassels to decorate bikes (and bike helmets), which is fun but takes about 5 minutes max, so I don't necessarily recommend it as a party game ;), but you can email if you don't know how and want directions ...
shells? if you get a box of 'glue dots' from a craft store, so noone has to mess with liquid glue, you could see who makes the craziest shell critter (glue dots come on a roll, in a cardboard box, and you'll have to ask the craft store people where they are) ... my kids had the grandest time with the last bag of shells I found at Goodwill, making 'houses' for the little carved-stone animals that the Goodwill people tossed in with the shells (those carved-stone animals are super cute and not too expensive, if you can get to a mall that has some sort of bead store or rockhound store ... although they will set off any very conservative Christians because they are of course at least based on if not actually "totem" animals)
those glass "pebbles"? seems like there are whole pages of sticky at craft stores, where you peel off a covering paper and the page under it is sticky? that would be all kinds of fun to stick glass pebbles to, then maybe shake some sand over it to cover any remaining exposed sticky
anyhow, those are just the last few things I've seen at Goodwill that seems like kids would just want to dig their hands around in them whether or not you provide a structured activity ;) ... this summer I watched a kid methodically use almost a whole roll of tape and an entire package of those craft popsicle sticks to make herself a 'purse' ... you just never can tell with kids :). Goodwill also often has baggies or jars of sequins, mardi gras beads, ribbons ... jumpropes, balls ... if you're lucky you might find stickers and they can decorate their party cups ...
a pinata is a FASCINATING object for most five year olds ... I stuffed one with Goodwill mardi gras beads and shells (over a soft surface, so the shells didn't break), with a handful of jelly beans to acknowledge the "candy" expectation ... noone seemed disappointed that the prizes weren't all candy ;) ... make sure you bring a banging stick, unless you go the Cuban route and sew ribbons through the bottom so the kids cooperatively pull it apart ...
'think that's all for now :).