No, not less difficult to stop.
Since you said you'd only visit 3 cities besides Dublin and London I assumed that you'd be using point-to-point tickets, as these are usually cheaper than a railpass.
Amsterdam-Berlin is normally 120 EUR, stopping at Q'burg and using regional trains you could have made it for 80 EUR.
Quedlinburg is not directly on the Amsterdam-Berlin train line, you'd have to go to Magdeburg and change there. If you do this, drop me a line since this is my "backyard".
You'd need about a day to see Q'burg, but it would totally be worth it. Quedlinburg is one of the few cities in Germany with an intact medievial city center, lots of old wood timbered houses and a castle with a world-famous historical treasure. The whole city is a UNESCO world heritage site and totally deserves this title.
And if you are a train freak, you should take a look at the narrow-gauge steam train that runs through the Harz mountains.
I had looked into point-to-point tickets but because of the strength of the Euro compared to the Canadian Dollar, buying a rail pass was more economical and also allows me a few day trips on the pass.
Since I do have a few extra days of travel, would it be worth the effort to take a day trip to Quedlinburg from Berlin?
Unfortunately the rail connections from Berlin to Quedlinburg are not so good. It would take you about 3 hours to get to Quedlinburg from Berlin, 2 hours of the trip you'd be travelling in the directing of Amsterdam. It thus makes a lot of sense to break up your trip from Amsterdam to Berlin either in Magdeburg or Quedlinburg.
There is a YHA/HI youth hostel in Quedlinburg, a bed with breakfast is 16,50 € plus bedsheets for 3.50 EUR plus 3 EUR if you are above 27.
Alternatively you could couchsurf in Magdeburg. Magdeburg is a university town that doesn't get much tourist traffic, but has a lot of couchsurfing members, myself included. You should be able to find somebody without too much problem.
As for Dublin I agree with Sam's recommendation of Avalon House. I've stayed there multiple times and it's a friendly place.
In terms of Paris, I had tried to stay at one of the two BVJ hostels last time I went, but they were already booked up. The slight downside of their two places is that you have to book directly through them (at least I'm pretty sure.) Where I ended up staying was in two of the three MIJE hostels, which were nice if slightly on the pricier end for hostels. Personally I preferred the Fauconnier to Maubuisson as the later only had salon style doors into the bathrooms, making it a lot noisier/distracting if someone had to get up early. Neither had lockers or such in the rooms or common area, though there was a secure room if you were out for the day.
For hostels, I'd go with the ones recomended on here. Flying Pig in amsterdam is great, heart of gold/the circus in Berlin are also great.
For London I'd avoid The Generator, its a soulless dreary place down a grimey alley.
I'd also recommend sandemans tours in the cities, i usually get to a new city and go on the tour on the first day. Gives you a good overview of the city and orientates you a bit. (http://www.neweuropetours.eu/)
Hostel Meeting Place (Red Light Amsterdam) is just fantastic and so cheap. A 5 minute walk to just about the whole of the Red Light (don't be put off by the name - it's an amazingly friendly part of Europe's greatest city) and a great breakfast too.
Thanks for the tips. Hostel Meeting Place is actually one of my top choices for somewhere to stay in amsterdam so I'm glad that it's a good choice
I fished out my old receipt to get a price for you (it's €18 a night including breakfast).... Got the name slightly wrong too. It's Hostel Meeting 'Point', not 'Place'.
It is very good. There are a lot of people that have this weird idea, that because it's in the Amsterdam Red Light, it's gonna be full of prostitutes, drug pushers etc. Obviously they've never been there. Yes, the Red Light has coffee shops and sex shops too. But it's safe, very clean and the hospitality in the area is just wonderful - otherwise I wouldn't recommend it and certainly wouldn't stay there myself.
Hostel Meeting Point is a great centre for young people (although age is not an issue at reception) to stay a night - or two.
One piece of advice.... If you're gonna stay there, try and book in advance (it's very busy throughout the year) and if you pay by card on turning up (either debit or credit), it's a little more expensive than paying cash. There is an ATM machine just across the main canal past The Grasshopper, near to the internet cafe and cigar shop. It's just a 5 minute walk from Hostel Meeting Place.
Ok thanks a lot. This is really helpful. I know what you mean about people thinking the red light district is shady, when everything I've heard is all very positive