First off, welcome back!
I don't know if anyone mentioned profession-wise what is popular for things nowadays in the community, but Speed Clears are still very common to do in the community. Speed Clear-wise, at least one Assassin with Shadow Form and Shroud of Distress is still used in every single speed clear run except for The Deep [although you can tank Deep on Sin, it's mostly used for just HM runs and not Speed Clears] for either tanking or team composition or whatever.
The spike roles are a lot different now than back then with the SF Nukers or MS Echo Nuker and B/P and such that you probably would have seen around. Today, melee spikes are done by Dervish for the most part and caster spikes are mainly Mesmer. There will always be to be more than one method, however these are the ones who have acquired the fastest times so far. Another form of clearing areas for "rare" items that became popular would be Dungeon Speed Clears in Eye of the North [EotN]. I think the most overall Dungeons farmed would be Shards of Orr [SoOSC], Bogroots [BogSC], and Rragar's [RragarSC]. I'm not sure where the appropriate place to list all of these would be, but I can list the popular ones that I at least know about. In all Speed Clears it's common, and easier, to learn from the spiker role first.
Note: All DungeonSC's can potentially be formed at Vlox's Falls.
Here's a small list of some spiker roles per area:
Fissure of Woe - Dervish Spike [Core]
Domain of Anguish - Mesmer Spike [Endgame NF]
Shards of Orr - Ranger Spike [Dungeon - leaves from Vlox's Falls]
Bogroots - Dervish Spike [Dungeon - leaves from Gadds Encampment]
Rragar's - Dervish Spike [Dungeon - leaves from Doomlore Shrine]
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As far as other dungeons go, there is a couple ways to do Cathedral of Flames with sin spikes or derv spikes and whatnot. You'll just have to figure out what is the popular way for the people you go with when you are able to. Frostmaw, Slavers, Kathandrax, Ooze, Oola's, and Ravens are done with sins generally. The builds vary.
If you pose an interest in Speed Clears, acquiring the builds can be as easy as asking people in game or you can contact me in game and I can send you lots!
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As far as everything else PvE goes, I personally still do chest running & farming of sorts for "Oldschool Items" (i.e. items with no Inscription Slot / also called OS items). Some of these can sell for quite a bit and come with mods that cannot be acquired by other means of playing in Nightfall or Eye of the North campaigns (i.e. +10 Armor versus Creature types like Demon, Dwarves, Plants, etc). Note that also if you want +10 vs Fire AND -2/3 Damage received mod on a shield, you can only get this from an OS Shield as both mods come in inscriptions and only 1 inscription can be applied to a shield). Also, there are skins that come in OS form than cannot be replicated with inscription items. However, the same goes for inscription items.
I'm sure if you are an old player you may have some "Prenerf" (no longer exist as drops) items on your account as well. Before you go salvaging and merching items I'd have someone trustworthy check out your wares in game or something to determine if it has value nowadays, even if it didn't in the past. I'm willing to help you out with that if you would want it as well as other Guru members I'm sure.
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And finally, if you need anymore info or help, there are numerous guilds out there who will take you and guide you along in your attempt to get back into GW1. Best advice, have some fun and go try everything. See what you enjoy!

Good luck!
< For anymore advice/help/etc. my IGN [in game name] is the same as my Guru name.