I finished my grand jury service today (see here and here ). Serving has educational and entertainment value and was no hardship for me so I don't regret being selected. However as I noted earlier I question whether grand juries are worth the expense. Based on my experience I doubt they provide any significant protection for the accused (compared to the preliminary hearing before a judge used in many states). Another argument for them is tradition but I don't find this compelling. I suppose there is some value in bringing a diverse group of citizens together to perform a civic ritual.
Some details of serving in Westchester. Although the summons said otherwise there was in fact plenty of juror parking. Theoretically our day was 10 am to 5 pm (with time for lunch) but in practice it averaged less than half that. You do need to allow some extra time (20 minutes on a bad day but usually less) to get through the metal detectors in the courthouse lobby. Serving exempts you for a while (8 years state, 4 years federal if I remember correctly) from future jury service.