In TS4 I throw parties rarely. Basically only weddings. In TS3 I used to throw all kinds of parties. Weddings, funerals, basic parties and I loved to throw the fundraisers. I don't know what these events were called but when you had a sim in a certain career then sometimes they had to throw a fancy party and raise a lot of money. I absolutely LOVED those. So cool.
The main reason is that I "grew up". Or I had to :D When I got TS3 I was 19-20yo, in the UK as an au pair so I have plenty of free time to play. Before I went to the UK I was a huuuge party girl. But that was because of my boyfriend. When I got back home to my country I met my husband and only like 2 month later TS4 came out, I was engaged and one month before my wedding. That time I got pregnant. So that's the reason I guess. I've never been on a party since.
Anyhow, I don't liek that events in TS4 are time limited. I want to choose when the events my sim throws end! It is frustrating.