well, as far as i'm concerned it DOES matter who the party is for... are you having a bunch of your friends? or does your baby go to a playgroup, from which you will want to invite people with their kids? will you want to have it at a small, intimate restaurant or do you want to rent a grand ballroom in a hotel?
do you want catering for adults? or kids' food? do you want a children's entertainer? or would you prefer more sophisticated entertainment?
for my son's first birthday, we had a picnic in the park. no need for a party planner.... ordered take away food, baked my own cake (it's a tradition now that the kids are 5 & 7), bought a pinata for the older kids etc.
i buy all of the party treats in sham shui po (everyone that comes raves about my finds)....
i just did my two kids' party again (they are only 6 days apart)... KFC, homemade cake, rented a bouncy castle. kids had a ball... cost for the total parting, including 2 birthday kids? less than $3000... now, i know others who would spend that much on a venue rental alone... so, it really comes down to what is important to you....
without giving more details of what you are looking for, how do you expect people to offer ideas? you didn't even offer a budget idea....