would like recommendations for a hotel in leiden netherlands
The best hotels in the city might be Boutique Hotel Steenhof Suites, Boutique Hotel Huys van Leyden, or Boutique Hotel d'Oude Morsch. If you're simply looking for a basic place convenient to the train station, then there's an Ibis Hotel just across the street from the station and a Hotel Golden Tulip close by.
There's a Holiday Inn and a Valk de Valk on the A4 towards the airport.
Car or bus/train?
What would you like to be near?
We were in Leiden a couple of years ago, and stayed at the Hotel Nieuwe Minerva, Boommarkt 23. It was about €115 per night, in early May. It's not fancy, but it's in a great location, with friendly, helpful staff. It's in easy walking distance from the train station, and there are many restaurants nearby.
There a nice lounge area with a small library, and the breakfast is good. I don't remember whether or not there was an elevator; I don't think there was. Our room was big and comfortable, but there was a step down into the en suite bathroom that caused us some concern.
We appreciated their opening the breakfast room early for us on our departure day. If we ever return to Leiden, and we certainly hope to, we will gladly stay there again.
Nigel makes a good point - what type of transport you have makes a huge difference as to where you stay in Leiden. As it's quite close to The Hague, I bike through there a few times a week. Leiden is a university town - since the late 1500's - and is second only to Amsterdam in the number of canals. Thus, it has a large "old-town" city center. Great for bikes - not so much for parking cars.
So if you're training in and out - and this is just a stopover - stay at one of the hotels adjacent to the train station. If this town is a "multi-day stop" for you (and there's plenty to see), then stay in the Old-Town city-center. After all, this is the birthplace of Rembrandt - why not stay in a historic hotel location!
If you have a car, the Holiday inn is a viable option. I'm not familiar with a Valk de Valk hotel on the A4, but there is the Van der Valk Hotel Leiden, located just off the A44. It's a wonderful hotel, located on a canal. They are currently constructing an exit on the A44 for better access to this hotel. From here, you currently have to drive back toward town to get on the A44 (passing the Holiday Inn on the way). From the A44, you can head to the Airport - or in the other direction on the A44 - come to my hometown, The Hague. (They've been working on the exit ramps for this intersection for a year so hopefully, it will be done soon!). If you're planning to walk to explore Leiden, both these hotels are roughly 3 KM from the city center. (I'd see them as good stopover options if you have a car).
We love exploring Leiden - Many teachers at my wife's school choose Leiden as their home because of it's proximity to Wassenaar. They say there's always something to do there. And if you're visiting at Christmas, their Holiday Market is perhaps the only seasonal "floating market" in the NL (although - unfortunately - not this year).
We stayed at De Doelen for 3 nights last October. Great location on Rapenburg canal, nice room for about 115 Euros per night. Seemed to be family run; I don't think there was an elevator but they do have rooms on the first floor.
My wife and I stayed four nights at the Boutique Hotel d'Oude Morsch in February of this year (2020). We had a great stay and I would highly recommend, based on our experience. The hotel is about a 10 minute walk from the train station and very well located to everything walkable in Leiden. We booked a Large Superior Room since we were staying four nights and it was very comfortable and roomy. Staff were very attentive and hotel seemed well run. Would stay there again, for sure.