Yatish, I would think that hiring a vehicle + driver would be the easiest. Go to the nearest travel agent, and you'll find Innovas and Sumos for rent. It will probably cost you around Rs. 6 per km. Travel time to Shirdi is likely to be around 4 hours.

We went there by bus last year, which took around 5 hours one way. Many people prefer to leave at night around 10-11pm and reach there in morning to attend 5am Aarti. We left in morning and reached there by noon. After darshan we took lunch and caught a bus for pune back. We had to be in queue for nearly 1hour. This time can be even long on certain days(1hour is quite common, it can be more ususally). There is provision for old-age people, so if you have senior citizens with you, they can go in seperate q for seniors and that will take less time in Q.

Though I do not have a first hand experience, i have heard that these travel companies (e.g. Prasanna, sachin travels etc) have "Shirdi tours" as package tours. The model is that you leave pune today night at say 10pm. They have a place arranged for you where you can have bath in the morning, you can have darshan and they get you back by tomorrow night.

The other place you can visit is Shingnapur, i think the package tour covers that too. I do not have an idea about the fares.

One more point. There are many good hotels to stay at in Shirdi. (Checkout any online travel site) So you can consider making an overnight trip there as well, and cover nearby places.