Shimla as I have know it may once have been a idyllic hill station with aura of British Raj but no more. It has been exploited so much by the tourists and vendors providing logistics that you hardly feel like being in a hill station except the lanscape and weather which thankfully cant be tampered.
<p>
During season (Apr-June), there are too many people out there in Shimla and rates of acco, commodities and services (taxi etc.) skyrocket. Parking is a huge problem if you are taking your own vehicle. Not an inch has been left on the hill face on which Shimla is built, all concrete structures everywhere. With all the amenities of cities demamded/provided, garbage disposal is huge problem.
<p>
The best would be go for day trips around Shimla and that is what I did mostly. Chadwick Falls (near Summer Hill), Tara Devi, Sankat Mochan, Kufri, Chail, Mashobara, Dhengu Tample (via Sanjauli) are few places you could drive and then trek. Being in a group would be fun. On days when sky is clear, you could watch snow-clad Dhauladhar mountains at the horizon.
<p>
Overall, its a hill station with overdose of tourists and vendors.